greenplumn heapam 源码
greenplumn heapam 代码
文件路径：/src/backend/access/heap/heapam.c
/*-------------------------------------------------------------------------
*
* heapam.c
* heap access method code
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/access/heap/heapam.c
*
*
* INTERFACE ROUTINES
* heap_beginscan - begin relation scan
* heap_rescan - restart a relation scan
* heap_endscan - end relation scan
* heap_getnext - retrieve next tuple in scan
* heap_fetch - retrieve tuple with given tid
* heap_insert - insert tuple into a relation
* heap_multi_insert - insert multiple tuples into a relation
* heap_delete - delete a tuple from a relation
* heap_update - replace a tuple in a relation with another tuple
* heap_sync - sync heap, for when no WAL has been written
*
* NOTES
* This file contains the heap_ routines which implement
* the POSTGRES heap access method used for all POSTGRES
* relations.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/bufmask.h"
#include "access/genam.h"
#include "access/heapam.h"
#include "access/heapam_xlog.h"
#include "access/hio.h"
#include "access/multixact.h"
#include "access/parallel.h"
#include "access/relscan.h"
#include "access/sysattr.h"
#include "access/tableam.h"
#include "access/transam.h"
#include "access/tuptoaster.h"
#include "access/valid.h"
#include "access/visibilitymap.h"
#include "access/xact.h"
#include "access/xlog.h"
#include "access/xloginsert.h"
#include "access/xlogutils.h"
#include "catalog/catalog.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "port/atomics.h"
#include "storage/bufmgr.h"
#include "storage/freespace.h"
#include "storage/lmgr.h"
#include "storage/predicate.h"
#include "storage/procarray.h"
#include "storage/smgr.h"
#include "storage/spin.h"
#include "storage/standby.h"
#include "utils/datum.h"
#include "utils/gpexpand.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/relcache.h"
#include "utils/snapmgr.h"
#include "utils/spccache.h"
#include "catalog/oid_dispatch.h"
#include "cdb/cdbvars.h"
#include "utils/guc.h"
#include "utils/faultinjector.h"
static TM_Result heap_update_internal(Relation relation, ItemPointer otid, HeapTuple newtup,
CommandId cid, Snapshot crosscheck, bool wait,
TM_FailureData *tmfd, LockTupleMode *lockmode, bool simple);
static HeapTuple heap_prepare_insert(Relation relation, HeapTuple tup,
TransactionId xid, CommandId cid, int options, bool isFrozen);
static XLogRecPtr log_heap_update(Relation reln, Buffer oldbuf,
Buffer newbuf, HeapTuple oldtup,
HeapTuple newtup, HeapTuple old_key_tup,
bool all_visible_cleared, bool new_all_visible_cleared);
static Bitmapset *HeapDetermineModifiedColumns(Relation relation,
Bitmapset *interesting_cols,
HeapTuple oldtup, HeapTuple newtup);
static bool heap_acquire_tuplock(Relation relation, ItemPointer tid,
LockTupleMode mode, LockWaitPolicy wait_policy,
bool *have_tuple_lock);
static void compute_new_xmax_infomask(TransactionId xmax, uint16 old_infomask,
uint16 old_infomask2, TransactionId add_to_xmax,
LockTupleMode mode, bool is_update,
TransactionId *result_xmax, uint16 *result_infomask,
uint16 *result_infomask2);
static TM_Result heap_lock_updated_tuple(Relation rel, HeapTuple tuple,
ItemPointer ctid, TransactionId xid,
LockTupleMode mode);
static void GetMultiXactIdHintBits(MultiXactId multi, uint16 *new_infomask,
uint16 *new_infomask2);
static TransactionId MultiXactIdGetUpdateXid(TransactionId xmax,
uint16 t_infomask);
static bool DoesMultiXactIdConflict(MultiXactId multi, uint16 infomask,
LockTupleMode lockmode, bool *current_is_member);
static void MultiXactIdWait(MultiXactId multi, MultiXactStatus status, uint16 infomask,
Relation rel, ItemPointer ctid, XLTW_Oper oper,
int *remaining);
static bool ConditionalMultiXactIdWait(MultiXactId multi, MultiXactStatus status,
uint16 infomask, Relation rel, int *remaining);
static XLogRecPtr log_heap_new_cid(Relation relation, HeapTuple tup);
static HeapTuple ExtractReplicaIdentity(Relation rel, HeapTuple tup, bool key_modified,
bool *copy);
/*
* Each tuple lock mode has a corresponding heavyweight lock, and one or two
* corresponding MultiXactStatuses (one to merely lock tuples, another one to
* update them). This table (and the macros below) helps us determine the
* heavyweight lock mode and MultiXactStatus values to use for any particular
* tuple lock strength.
*
* Don't look at lockstatus/updstatus directly! Use get_mxact_status_for_lock
* instead.
*/
static const struct
{
LOCKMODE hwlock;
int lockstatus;
int updstatus;
}
tupleLockExtraInfo[MaxLockTupleMode + 1] =
{
{ /* LockTupleKeyShare */
AccessShareLock,
MultiXactStatusForKeyShare,
-1 /* KeyShare does not allow updating tuples */
},
{ /* LockTupleShare */
RowShareLock,
MultiXactStatusForShare,
-1 /* Share does not allow updating tuples */
},
{ /* LockTupleNoKeyExclusive */
ExclusiveLock,
MultiXactStatusForNoKeyUpdate,
MultiXactStatusNoKeyUpdate
},
{ /* LockTupleExclusive */
AccessExclusiveLock,
MultiXactStatusForUpdate,
MultiXactStatusUpdate
}
};
/* Get the LOCKMODE for a given MultiXactStatus */
#define LOCKMODE_from_mxstatus(status) \
(tupleLockExtraInfo[TUPLOCK_from_mxstatus((status))].hwlock)
/*
* Acquire heavyweight locks on tuples, using a LockTupleMode strength value.
* This is more readable than having every caller translate it to lock.h's
* LOCKMODE.
*/
#define LockTupleTuplock(rel, tup, mode) \
LockTuple((rel), (tup), tupleLockExtraInfo[mode].hwlock)
#define UnlockTupleTuplock(rel, tup, mode) \
UnlockTuple((rel), (tup), tupleLockExtraInfo[mode].hwlock)
#define ConditionalLockTupleTuplock(rel, tup, mode) \
ConditionalLockTuple((rel), (tup), tupleLockExtraInfo[mode].hwlock)
#ifdef USE_PREFETCH
/*
* heap_compute_xid_horizon_for_tuples and xid_horizon_prefetch_buffer use
* this structure to coordinate prefetching activity.
*/
typedef struct
{
BlockNumber cur_hblkno;
int next_item;
int nitems;
ItemPointerData *tids;
} XidHorizonPrefetchState;
#endif
/*
* This table maps tuple lock strength values for each particular
* MultiXactStatus value.
*/
static const int MultiXactStatusLock[MaxMultiXactStatus + 1] =
{
LockTupleKeyShare, /* ForKeyShare */
LockTupleShare, /* ForShare */
LockTupleNoKeyExclusive, /* ForNoKeyUpdate */
LockTupleExclusive, /* ForUpdate */
LockTupleNoKeyExclusive, /* NoKeyUpdate */
LockTupleExclusive /* Update */
};
/* Get the LockTupleMode for a given MultiXactStatus */
#define TUPLOCK_from_mxstatus(status) \
(MultiXactStatusLock[(status)])
/* ----------------------------------------------------------------
* heap support routines
* ----------------------------------------------------------------
*/
/* ----------------
* initscan - scan code common to heap_beginscan and heap_rescan
* ----------------
*/
static void
initscan(HeapScanDesc scan, ScanKey key, bool keep_startblock)
{
ParallelBlockTableScanDesc bpscan = NULL;
bool allow_strat;
bool allow_sync;
/*
* Determine the number of blocks we have to scan.
*
* It is sufficient to do this once at scan start, since any tuples added
* while the scan is in progress will be invisible to my snapshot anyway.
* (That is not true when using a non-MVCC snapshot. However, we couldn't
* guarantee to return tuples added after scan start anyway, since they
* might go into pages we already scanned. To guarantee consistent
* results for a non-MVCC snapshot, the caller must hold some higher-level
* lock that ensures the interesting tuple(s) won't change.)
*/
if (scan->rs_base.rs_parallel != NULL)
{
bpscan = (ParallelBlockTableScanDesc) scan->rs_base.rs_parallel;
scan->rs_nblocks = bpscan->phs_nblocks;
}
else
scan->rs_nblocks = RelationGetNumberOfBlocks(scan->rs_base.rs_rd);
/*
* If the table is large relative to NBuffers, use a bulk-read access
* strategy and enable synchronized scanning (see syncscan.c). Although
* the thresholds for these features could be different, we make them the
* same so that there are only two behaviors to tune rather than four.
* (However, some callers need to be able to disable one or both of these
* behaviors, independently of the size of the table; also there is a GUC
* variable that can disable synchronized scanning.)
*
* Note that table_block_parallelscan_initialize has a very similar test;
* if you change this, consider changing that one, too.
*/
if (!RelationUsesLocalBuffers(scan->rs_base.rs_rd) &&
scan->rs_nblocks > NBuffers / 4)
{
allow_strat = (scan->rs_base.rs_flags & SO_ALLOW_STRAT) != 0;
allow_sync = (scan->rs_base.rs_flags & SO_ALLOW_SYNC) != 0;
}
else
allow_strat = allow_sync = false;
if (allow_strat)
{
/* During a rescan, keep the previous strategy object. */
if (scan->rs_strategy == NULL)
scan->rs_strategy = GetAccessStrategy(BAS_BULKREAD);
}
else
{
if (scan->rs_strategy != NULL)
FreeAccessStrategy(scan->rs_strategy);
scan->rs_strategy = NULL;
}
if (scan->rs_base.rs_parallel != NULL)
{
/* For parallel scan, believe whatever ParallelTableScanDesc says. */
if (scan->rs_base.rs_parallel->phs_syncscan)
scan->rs_base.rs_flags |= SO_ALLOW_SYNC;
else
scan->rs_base.rs_flags &= ~SO_ALLOW_SYNC;
}
else if (keep_startblock)
{
/*
* When rescanning, we want to keep the previous startblock setting,
* so that rewinding a cursor doesn't generate surprising results.
* Reset the active syncscan setting, though.
*/
if (allow_sync && synchronize_seqscans)
scan->rs_base.rs_flags |= SO_ALLOW_SYNC;
else
scan->rs_base.rs_flags &= ~SO_ALLOW_SYNC;
}
else if (allow_sync && synchronize_seqscans)
{
scan->rs_base.rs_flags |= SO_ALLOW_SYNC;
scan->rs_startblock = ss_get_location(scan->rs_base.rs_rd, scan->rs_nblocks);
}
else
{
scan->rs_base.rs_flags &= ~SO_ALLOW_SYNC;
scan->rs_startblock = 0;
}
scan->rs_numblocks = InvalidBlockNumber;
scan->rs_inited = false;
scan->rs_ctup.t_data = NULL;
ItemPointerSetInvalid(&scan->rs_ctup.t_self);
scan->rs_cbuf = InvalidBuffer;
scan->rs_cblock = InvalidBlockNumber;
/* page-at-a-time fields are always invalid when not rs_inited */
/*
* copy the scan key, if appropriate
*/
if (key != NULL)
memcpy(scan->rs_base.rs_key, key, scan->rs_base.rs_nkeys * sizeof(ScanKeyData));
/*
* Currently, we only have a stats counter for sequential heap scans (but
* e.g for bitmap scans the underlying bitmap index scans will be counted,
* and for sample scans we update stats for tuple fetches).
*/
if (scan->rs_base.rs_flags & SO_TYPE_SEQSCAN)
pgstat_count_heap_scan(scan->rs_base.rs_rd);
}
/*
* heap_setscanlimits - restrict range of a heapscan
*
* startBlk is the page to start at
* numBlks is number of pages to scan (InvalidBlockNumber means "all")
*/
void
heap_setscanlimits(TableScanDesc sscan, BlockNumber startBlk, BlockNumber numBlks)
{
HeapScanDesc scan = (HeapScanDesc) sscan;
Assert(!scan->rs_inited); /* else too late to change */
/* else rs_startblock is significant */
Assert(!(scan->rs_base.rs_flags & SO_ALLOW_SYNC));
/* Check startBlk is valid (but allow case of zero blocks...) */
Assert(startBlk == 0 || startBlk < scan->rs_nblocks);
scan->rs_startblock = startBlk;
scan->rs_numblocks = numBlks;
}
/*
* heapgetpage - subroutine for heapgettup()
*
* This routine reads and pins the specified page of the relation.
* In page-at-a-time mode it performs additional work, namely determining
* which tuples on the page are visible.
*/
void
heapgetpage(TableScanDesc sscan, BlockNumber page)
{
HeapScanDesc scan = (HeapScanDesc) sscan;
Buffer buffer;
Snapshot snapshot;
Page dp;
int lines;
int ntup;
OffsetNumber lineoff;
ItemId lpp;
bool all_visible;
TransactionId t_xmin;
CommandId t_cid;
Assert(page < scan->rs_nblocks);
/* release previous scan buffer, if any */
if (BufferIsValid(scan->rs_cbuf))
{
ReleaseBuffer(scan->rs_cbuf);
scan->rs_cbuf = InvalidBuffer;
}
/*
* Be sure to check for interrupts at least once per page. Checks at
* higher code levels won't be able to stop a seqscan that encounters many
* pages' worth of consecutive dead tuples.
*/
CHECK_FOR_INTERRUPTS();
/* read page using selected strategy */
scan->rs_cbuf = ReadBufferExtended(scan->rs_base.rs_rd, MAIN_FORKNUM, page,
RBM_NORMAL, scan->rs_strategy);
scan->rs_cblock = page;
if (!(scan->rs_base.rs_flags & SO_ALLOW_PAGEMODE))
return;
buffer = scan->rs_cbuf;
snapshot = scan->rs_base.rs_snapshot;
/*
* Prune and repair fragmentation for the whole page, if possible.
*/
heap_page_prune_opt(scan->rs_base.rs_rd, buffer);
/*
* We must hold share lock on the buffer content while examining tuple
* visibility. Afterwards, however, the tuples we have found to be
* visible are guaranteed good as long as we hold the buffer pin.
*/
LockBuffer(buffer, BUFFER_LOCK_SHARE);
dp = BufferGetPage(buffer);
TestForOldSnapshot(snapshot, scan->rs_base.rs_rd, dp);
lines = PageGetMaxOffsetNumber(dp);
ntup = 0;
t_xmin = 0;
t_cid = 0;
/*
* If the all-visible flag indicates that all tuples on the page are
* visible to everyone, we can skip the per-tuple visibility tests.
*
* Note: In hot standby, a tuple that's already visible to all
* transactions in the master might still be invisible to a read-only
* transaction in the standby. We partly handle this problem by tracking
* the minimum xmin of visible tuples as the cut-off XID while marking a
* page all-visible on master and WAL log that along with the visibility
* map SET operation. In hot standby, we wait for (or abort) all
* transactions that can potentially may not see one or more tuples on the
* page. That's how index-only scans work fine in hot standby. A crucial
* difference between index-only scans and heap scans is that the
* index-only scan completely relies on the visibility map where as heap
* scan looks at the page-level PD_ALL_VISIBLE flag. We are not sure if
* the page-level flag can be trusted in the same way, because it might
* get propagated somehow without being explicitly WAL-logged, e.g. via a
* full page write. Until we can prove that beyond doubt, let's check each
* tuple for visibility the hard way.
*/
all_visible = PageIsAllVisible(dp) && !snapshot->takenDuringRecovery;
for (lineoff = FirstOffsetNumber, lpp = PageGetItemId(dp, lineoff);
lineoff <= lines;
lineoff++, lpp++)
{
if (ItemIdIsNormal(lpp))
{
HeapTupleData loctup;
bool valid;
HeapTupleHeader theader = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
loctup.t_tableOid = RelationGetRelid(scan->rs_base.rs_rd);
loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
loctup.t_len = ItemIdGetLength(lpp);
ItemPointerSet(&(loctup.t_self), page, lineoff);
if (all_visible)
{
valid = true;
}
else
{
/*
* GPDB: We have a one-item cache for the common case that a
* lot of tuples have the same visibility info. Don't use the
* cache, if the tuple was ever deleted, though (i.e. if xmax
* is valid, and not just for tuple-locking). We could cache
* the xmax too, but the visibility rules get more complicated
* with locked-only tuples and multi-XIDs, so it seems better
* to just give up early.
*/
bool use_cache;
if ((theader->t_infomask & HEAP_XMAX_INVALID) != 0 ||
HEAP_XMAX_IS_LOCKED_ONLY(theader->t_infomask))
use_cache = true;
else
use_cache = false;
if (use_cache &&
t_xmin == HeapTupleHeaderGetXmin(theader) &&
t_cid == HeapTupleHeaderGetRawCommandId(theader))
{
valid = true;
}
else
{
valid = HeapTupleSatisfiesVisibility(scan->rs_base.rs_rd,
&loctup, snapshot, buffer);
if (valid && use_cache)
{
t_xmin = HeapTupleHeaderGetXmin(loctup.t_data);
t_cid = HeapTupleHeaderGetRawCommandId(loctup.t_data);
}
}
}
CheckForSerializableConflictOut(valid, scan->rs_base.rs_rd,
&loctup, buffer, snapshot);
if (valid)
scan->rs_vistuples[ntup++] = lineoff;
}
}
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
Assert(ntup <= MaxHeapTuplesPerPage);
scan->rs_ntuples = ntup;
}
/* ----------------
* heapgettup - fetch next heap tuple
*
* Initialize the scan if not already done; then advance to the next
* tuple as indicated by "dir"; return the next tuple in scan->rs_ctup,
* or set scan->rs_ctup.t_data = NULL if no more tuples.
*
* dir == NoMovementScanDirection means "re-fetch the tuple indicated
* by scan->rs_ctup".
*
* Note: the reason nkeys/key are passed separately, even though they are
* kept in the scan descriptor, is that the caller may not want us to check
* the scankeys.
*
* Note: when we fall off the end of the scan in either direction, we
* reset rs_inited. This means that a further request with the same
* scan direction will restart the scan, which is a bit odd, but a
* request with the opposite scan direction will start a fresh scan
* in the proper direction. The latter is required behavior for cursors,
* while the former case is generally undefined behavior in Postgres
* so we don't care too much.
* ----------------
*/
static void
heapgettup(HeapScanDesc scan,
ScanDirection dir,
int nkeys,
ScanKey key)
{
HeapTuple tuple = &(scan->rs_ctup);
Snapshot snapshot = scan->rs_base.rs_snapshot;
bool backward = ScanDirectionIsBackward(dir);
BlockNumber page;
bool finished;
Page dp;
int lines;
OffsetNumber lineoff;
int linesleft;
ItemId lpp;
/*
* calculate next starting lineoff, given scan direction
*/
if (ScanDirectionIsForward(dir))
{
if (!scan->rs_inited)
{
/*
* return null immediately if relation is empty
*/
if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
if (scan->rs_base.rs_parallel != NULL)
{
ParallelBlockTableScanDesc pbscan =
(ParallelBlockTableScanDesc) scan->rs_base.rs_parallel;
table_block_parallelscan_startblock_init(scan->rs_base.rs_rd,
pbscan);
page = table_block_parallelscan_nextpage(scan->rs_base.rs_rd,
pbscan);
/* Other processes might have already finished the scan. */
if (page == InvalidBlockNumber)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
}
else
page = scan->rs_startblock; /* first page */
heapgetpage((TableScanDesc) scan, page);
lineoff = FirstOffsetNumber; /* first offnum */
scan->rs_inited = true;
}
else
{
/* continue from previously returned page/tuple */
page = scan->rs_cblock; /* current page */
lineoff = /* next offnum */
OffsetNumberNext(ItemPointerGetOffsetNumber(&(tuple->t_self)));
}
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(snapshot, scan->rs_base.rs_rd, dp);
lines = PageGetMaxOffsetNumber(dp);
/* page and lineoff now reference the physically next tid */
linesleft = lines - lineoff + 1;
}
else if (backward)
{
/* backward parallel scan not supported */
Assert(scan->rs_base.rs_parallel == NULL);
if (!scan->rs_inited)
{
/*
* return null immediately if relation is empty
*/
if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
/*
* Disable reporting to syncscan logic in a backwards scan; it's
* not very likely anyone else is doing the same thing at the same
* time, and much more likely that we'll just bollix things for
* forward scanners.
*/
scan->rs_base.rs_flags &= ~SO_ALLOW_SYNC;
/* start from last page of the scan */
if (scan->rs_startblock > 0)
page = scan->rs_startblock - 1;
else
page = scan->rs_nblocks - 1;
heapgetpage((TableScanDesc) scan, page);
}
else
{
/* continue from previously returned page/tuple */
page = scan->rs_cblock; /* current page */
}
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(snapshot, scan->rs_base.rs_rd, dp);
lines = PageGetMaxOffsetNumber(dp);
if (!scan->rs_inited)
{
lineoff = lines; /* final offnum */
scan->rs_inited = true;
}
else
{
lineoff = /* previous offnum */
OffsetNumberPrev(ItemPointerGetOffsetNumber(&(tuple->t_self)));
}
/* page and lineoff now reference the physically previous tid */
linesleft = lineoff;
}
else
{
/*
* ``no movement'' scan direction: refetch prior tuple
*/
if (!scan->rs_inited)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
page = ItemPointerGetBlockNumber(&(tuple->t_self));
if (page != scan->rs_cblock)
heapgetpage((TableScanDesc) scan, page);
/* Since the tuple was previously fetched, needn't lock page here */
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(snapshot, scan->rs_base.rs_rd, dp);
lineoff = ItemPointerGetOffsetNumber(&(tuple->t_self));
lpp = PageGetItemId(dp, lineoff);
Assert(ItemIdIsNormal(lpp));
tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
tuple->t_len = ItemIdGetLength(lpp);
return;
}
/*
* advance the scan until we find a qualifying tuple or run out of stuff
* to scan
*/
lpp = PageGetItemId(dp, lineoff);
for (;;)
{
CHECK_FOR_INTERRUPTS();
while (linesleft > 0)
{
if (ItemIdIsNormal(lpp))
{
bool valid;
tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
tuple->t_len = ItemIdGetLength(lpp);
ItemPointerSet(&(tuple->t_self), page, lineoff);
/*
* if current tuple qualifies, return it.
*/
valid = HeapTupleSatisfiesVisibility(scan->rs_base.rs_rd,
tuple,
snapshot,
scan->rs_cbuf);
CheckForSerializableConflictOut(valid, scan->rs_base.rs_rd,
tuple, scan->rs_cbuf,
snapshot);
if (valid && key != NULL)
HeapKeyTest(tuple, RelationGetDescr(scan->rs_base.rs_rd),
nkeys, key, valid);
if (valid)
{
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
return;
}
}
/*
* otherwise move to the next item on the page
*/
--linesleft;
if (backward)
{
--lpp; /* move back in this page's ItemId array */
--lineoff;
}
else
{
++lpp; /* move forward in this page's ItemId array */
++lineoff;
}
}
/*
* if we get here, it means we've exhausted the items on this page and
* it's time to move to the next.
*/
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
/*
* advance to next/prior page and detect end of scan
*/
if (backward)
{
finished = (page == scan->rs_startblock) ||
(scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false);
if (page == 0)
page = scan->rs_nblocks;
page--;
}
else if (scan->rs_base.rs_parallel != NULL)
{
ParallelBlockTableScanDesc pbscan =
(ParallelBlockTableScanDesc) scan->rs_base.rs_parallel;
page = table_block_parallelscan_nextpage(scan->rs_base.rs_rd,
pbscan);
finished = (page == InvalidBlockNumber);
}
else
{
page++;
if (page >= scan->rs_nblocks)
page = 0;
finished = (page == scan->rs_startblock) ||
(scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false);
/*
* Report our new scan position for synchronization purposes. We
* don't do that when moving backwards, however. That would just
* mess up any other forward-moving scanners.
*
* Note: we do this before checking for end of scan so that the
* final state of the position hint is back at the start of the
* rel. That's not strictly necessary, but otherwise when you run
* the same query multiple times the starting position would shift
* a little bit backwards on every invocation, which is confusing.
* We don't guarantee any specific ordering in general, though.
*/
if (scan->rs_base.rs_flags & SO_ALLOW_SYNC)
ss_report_location(scan->rs_base.rs_rd, page);
}
/*
* return NULL if we've exhausted all the pages
*/
if (finished)
{
if (BufferIsValid(scan->rs_cbuf))
ReleaseBuffer(scan->rs_cbuf);
scan->rs_cbuf = InvalidBuffer;
scan->rs_cblock = InvalidBlockNumber;
tuple->t_data = NULL;
scan->rs_inited = false;
return;
}
heapgetpage((TableScanDesc) scan, page);
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(snapshot, scan->rs_base.rs_rd, dp);
lines = PageGetMaxOffsetNumber((Page) dp);
linesleft = lines;
if (backward)
{
lineoff = lines;
lpp = PageGetItemId(dp, lines);
}
else
{
lineoff = FirstOffsetNumber;
lpp = PageGetItemId(dp, FirstOffsetNumber);
}
}
}
/* ----------------
* heapgettup_pagemode - fetch next heap tuple in page-at-a-time mode
*
* Same API as heapgettup, but used in page-at-a-time mode
*
* The internal logic is much the same as heapgettup's too, but there are some
* differences: we do not take the buffer content lock (that only needs to
* happen inside heapgetpage), and we iterate through just the tuples listed
* in rs_vistuples[] rather than all tuples on the page. Notice that
* lineindex is 0-based, where the corresponding loop variable lineoff in
* heapgettup is 1-based.
* ----------------
*/
static void
heapgettup_pagemode(HeapScanDesc scan,
ScanDirection dir,
int nkeys,
ScanKey key)
{
HeapTuple tuple = &(scan->rs_ctup);
bool backward = ScanDirectionIsBackward(dir);
BlockNumber page;
bool finished;
Page dp;
int lines;
int lineindex;
OffsetNumber lineoff;
int linesleft;
ItemId lpp;
/*
* calculate next starting lineindex, given scan direction
*/
if (ScanDirectionIsForward(dir))
{
if (!scan->rs_inited)
{
/*
* return null immediately if relation is empty
*/
if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
if (scan->rs_base.rs_parallel != NULL)
{
ParallelBlockTableScanDesc pbscan =
(ParallelBlockTableScanDesc) scan->rs_base.rs_parallel;
table_block_parallelscan_startblock_init(scan->rs_base.rs_rd,
pbscan);
page = table_block_parallelscan_nextpage(scan->rs_base.rs_rd,
pbscan);
/* Other processes might have already finished the scan. */
if (page == InvalidBlockNumber)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
}
else
page = scan->rs_startblock; /* first page */
heapgetpage((TableScanDesc) scan, page);
lineindex = 0;
scan->rs_inited = true;
}
else
{
/* continue from previously returned page/tuple */
page = scan->rs_cblock; /* current page */
lineindex = scan->rs_cindex + 1;
}
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, dp);
lines = scan->rs_ntuples;
/* page and lineindex now reference the next visible tid */
linesleft = lines - lineindex;
}
else if (backward)
{
/* backward parallel scan not supported */
Assert(scan->rs_base.rs_parallel == NULL);
if (!scan->rs_inited)
{
/*
* return null immediately if relation is empty
*/
if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
/*
* Disable reporting to syncscan logic in a backwards scan; it's
* not very likely anyone else is doing the same thing at the same
* time, and much more likely that we'll just bollix things for
* forward scanners.
*/
scan->rs_base.rs_flags &= ~SO_ALLOW_SYNC;
/* start from last page of the scan */
if (scan->rs_startblock > 0)
page = scan->rs_startblock - 1;
else
page = scan->rs_nblocks - 1;
heapgetpage((TableScanDesc) scan, page);
}
else
{
/* continue from previously returned page/tuple */
page = scan->rs_cblock; /* current page */
}
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, dp);
lines = scan->rs_ntuples;
if (!scan->rs_inited)
{
lineindex = lines - 1;
scan->rs_inited = true;
}
else
{
lineindex = scan->rs_cindex - 1;
}
/* page and lineindex now reference the previous visible tid */
linesleft = lineindex + 1;
}
else
{
/*
* ``no movement'' scan direction: refetch prior tuple
*/
if (!scan->rs_inited)
{
Assert(!BufferIsValid(scan->rs_cbuf));
tuple->t_data = NULL;
return;
}
page = ItemPointerGetBlockNumber(&(tuple->t_self));
if (page != scan->rs_cblock)
heapgetpage((TableScanDesc) scan, page);
/* Since the tuple was previously fetched, needn't lock page here */
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, dp);
lineoff = ItemPointerGetOffsetNumber(&(tuple->t_self));
lpp = PageGetItemId(dp, lineoff);
Assert(ItemIdIsNormal(lpp));
tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
tuple->t_len = ItemIdGetLength(lpp);
/* check that rs_cindex is in sync */
Assert(scan->rs_cindex < scan->rs_ntuples);
Assert(lineoff == scan->rs_vistuples[scan->rs_cindex]);
return;
}
/*
* advance the scan until we find a qualifying tuple or run out of stuff
* to scan
*/
for (;;)
{
CHECK_FOR_INTERRUPTS();
while (linesleft > 0)
{
lineoff = scan->rs_vistuples[lineindex];
lpp = PageGetItemId(dp, lineoff);
Assert(ItemIdIsNormal(lpp));
tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
tuple->t_len = ItemIdGetLength(lpp);
ItemPointerSet(&(tuple->t_self), page, lineoff);
/*
* if current tuple qualifies, return it.
*/
if (key != NULL)
{
bool valid;
HeapKeyTest(tuple, RelationGetDescr(scan->rs_base.rs_rd),
nkeys, key, valid);
if (valid)
{
scan->rs_cindex = lineindex;
return;
}
}
else
{
scan->rs_cindex = lineindex;
return;
}
/*
* otherwise move to the next item on the page
*/
--linesleft;
if (backward)
--lineindex;
else
++lineindex;
}
/*
* if we get here, it means we've exhausted the items on this page and
* it's time to move to the next.
*/
if (backward)
{
finished = (page == scan->rs_startblock) ||
(scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false);
if (page == 0)
page = scan->rs_nblocks;
page--;
}
else if (scan->rs_base.rs_parallel != NULL)
{
ParallelBlockTableScanDesc pbscan =
(ParallelBlockTableScanDesc) scan->rs_base.rs_parallel;
page = table_block_parallelscan_nextpage(scan->rs_base.rs_rd,
pbscan);
finished = (page == InvalidBlockNumber);
}
else
{
page++;
if (page >= scan->rs_nblocks)
page = 0;
finished = (page == scan->rs_startblock) ||
(scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false);
/*
* Report our new scan position for synchronization purposes. We
* don't do that when moving backwards, however. That would just
* mess up any other forward-moving scanners.
*
* Note: we do this before checking for end of scan so that the
* final state of the position hint is back at the start of the
* rel. That's not strictly necessary, but otherwise when you run
* the same query multiple times the starting position would shift
* a little bit backwards on every invocation, which is confusing.
* We don't guarantee any specific ordering in general, though.
*/
if (scan->rs_base.rs_flags & SO_ALLOW_SYNC)
ss_report_location(scan->rs_base.rs_rd, page);
}
/*
* return NULL if we've exhausted all the pages
*/
if (finished)
{
if (BufferIsValid(scan->rs_cbuf))
ReleaseBuffer(scan->rs_cbuf);
scan->rs_cbuf = InvalidBuffer;
scan->rs_cblock = InvalidBlockNumber;
tuple->t_data = NULL;
scan->rs_inited = false;
return;
}
heapgetpage((TableScanDesc) scan, page);
dp = BufferGetPage(scan->rs_cbuf);
TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, dp);
lines = scan->rs_ntuples;
linesleft = lines;
if (backward)
lineindex = lines - 1;
else
lineindex = 0;
}
}
#if defined(DISABLE_COMPLEX_MACRO)
/*
* This is formatted so oddly so that the correspondence to the macro
* definition in access/htup_details.h is maintained.
*/
Datum
fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
bool *isnull)
{
return (
(attnum) > 0 ?
(
(*(isnull) = false),
HeapTupleNoNulls(tup) ?
(
TupleDescAttr((tupleDesc), (attnum) - 1)->attcacheoff >= 0 ?
(
fetchatt(TupleDescAttr((tupleDesc), (attnum) - 1),
(char *) (tup)->t_data + (tup)->t_data->t_hoff +
TupleDescAttr((tupleDesc), (attnum) - 1)->attcacheoff)
)
:
nocachegetattr((tup), (attnum), (tupleDesc))
)
:
(
att_isnull((attnum) - 1, (tup)->t_data->t_bits) ?
(
(*(isnull) = true),
(Datum) NULL
)
:
(
nocachegetattr((tup), (attnum), (tupleDesc))
)
)
)
:
(
(Datum) NULL
)
);
}
#endif /* defined(DISABLE_COMPLEX_MACRO) */
/* ----------------------------------------------------------------
* heap access method interface
* ----------------------------------------------------------------
*/
TableScanDesc
heap_beginscan(Relation relation, Snapshot snapshot,
int nkeys, ScanKey key,
ParallelTableScanDesc parallel_scan,
uint32 flags)
{
HeapScanDesc scan;
/*
* increment relation ref count while scanning relation
*
* This is just to make really sure the relcache entry won't go away while
* the scan has a pointer to it. Caller should be holding the rel open
* anyway, so this is redundant in all normal scenarios...
*/
RelationIncrementReferenceCount(relation);
/*
* allocate and initialize scan descriptor
*/
scan = (HeapScanDesc) palloc(sizeof(HeapScanDescData));
scan->rs_base.rs_rd = relation;
scan->rs_base.rs_snapshot = snapshot;
scan->rs_base.rs_nkeys = nkeys;
scan->rs_base.rs_flags = flags;
scan->rs_base.rs_parallel = parallel_scan;
scan->rs_strategy = NULL; /* set in initscan */
/*
* Disable page-at-a-time mode if it's not a MVCC-safe snapshot.
*/
if (!(snapshot && IsMVCCSnapshot(snapshot)))
scan->rs_base.rs_flags &= ~SO_ALLOW_PAGEMODE;
/*
* For seqscan and sample scans in a serializable transaction, acquire a
* predicate lock on the entire relation. This is required not only to
* lock all the matching tuples, but also to conflict with new insertions
* into the table. In an indexscan, we take page locks on the index pages
* covering the range specified in the scan qual, but in a heap scan there
* is nothing more fine-grained to lock. A bitmap scan is a different
* story, there we have already scanned the index and locked the index
* pages covering the predicate. But in that case we still have to lock
* any matching heap tuples. For sample scan we could optimize the locking
* to be at least page-level granularity, but we'd need to add per-tuple
* locking for that.
*/
if (scan->rs_base.rs_flags & (SO_TYPE_SEQSCAN | SO_TYPE_SAMPLESCAN))
{
/*
* Ensure a missing snapshot is noticed reliably, even if the
* isolation mode means predicate locking isn't performed (and
* therefore the snapshot isn't used here).
*/
Assert(snapshot);
PredicateLockRelation(relation, snapshot);
}
/* we only need to set this up once */
scan->rs_ctup.t_tableOid = RelationGetRelid(relation);
/*
* we do this here instead of in initscan() because heap_rescan also calls
* initscan() and we don't want to allocate memory again
*/
if (nkeys > 0)
scan->rs_base.rs_key = (ScanKey) palloc(sizeof(ScanKeyData) * nkeys);
else
scan->rs_base.rs_key = NULL;
initscan(scan, key, false);
return (TableScanDesc) scan;
}
void
heap_rescan(TableScanDesc sscan, ScanKey key, bool set_params,
bool allow_strat, bool allow_sync, bool allow_pagemode)
{
HeapScanDesc scan = (HeapScanDesc) sscan;
if (set_params)
{
if (allow_strat)
scan->rs_base.rs_flags |= SO_ALLOW_STRAT;
else
scan->rs_base.rs_flags &= ~SO_ALLOW_STRAT;
if (allow_sync)
scan->rs_base.rs_flags |= SO_ALLOW_SYNC;
else
scan->rs_base.rs_flags &= ~SO_ALLOW_SYNC;
if (allow_pagemode && scan->rs_base.rs_snapshot &&
IsMVCCSnapshot(scan->rs_base.rs_snapshot))
scan->rs_base.rs_flags |= SO_ALLOW_PAGEMODE;
else
scan->rs_base.rs_flags &= ~SO_ALLOW_PAGEMODE;
}
/*
* unpin scan buffers
*/
if (BufferIsValid(scan->rs_cbuf))
ReleaseBuffer(scan->rs_cbuf);
/*
* reinitialize scan descriptor
*/
initscan(scan, key, true);
}
void
heap_endscan(TableScanDesc sscan)
{
HeapScanDesc scan = (HeapScanDesc) sscan;
/* Note: no locking manipulations needed */
/*
* unpin scan buffers
*/
if (BufferIsValid(scan->rs_cbuf))
ReleaseBuffer(scan->rs_cbuf);
/*
* decrement relation reference count and free scan descriptor storage
*/
RelationDecrementReferenceCount(scan->rs_base.rs_rd);
if (scan->rs_base.rs_key)
pfree(scan->rs_base.rs_key);
if (scan->rs_strategy != NULL)
FreeAccessStrategy(scan->rs_strategy);
if (scan->rs_base.rs_flags & SO_TEMP_SNAPSHOT)
UnregisterSnapshot(scan->rs_base.rs_snapshot);
pfree(scan);
}
#ifdef HEAPDEBUGALL
#define HEAPDEBUG_1 \
elog(DEBUG2, "heap_getnext([%s,nkeys=%d],dir=%d) called", \
RelationGetRelationName(scan->rs_rd), scan->rs_nkeys, (int) direction)
#define HEAPDEBUG_2 \
elog(DEBUG2, "heap_getnext returning EOS")
#define HEAPDEBUG_3 \
elog(DEBUG2, "heap_getnext returning tuple")
#else
#define HEAPDEBUG_1
#define HEAPDEBUG_2
#define HEAPDEBUG_3
#endif /* !defined(HEAPDEBUGALL) */
HeapTuple
heap_getnext(TableScanDesc sscan, ScanDirection direction)
{
HeapScanDesc scan = (HeapScanDesc) sscan;
/*
* This is still widely used directly, without going through table AM, so
* add a safety check. It's possible we should, at a later point,
* downgrade this to an assert. The reason for checking the AM routine,
* rather than the AM oid, is that this allows to write regression tests
* that create another AM reusing the heap handler.
*/
if (unlikely(sscan->rs_rd->rd_tableam != GetHeapamTableAmRoutine()))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg_internal("only heap AM is supported")));
/* Note: no locking manipulations needed */
HEAPDEBUG_1; /* heap_getnext( info ) */
if (scan->rs_base.rs_flags & SO_ALLOW_PAGEMODE)
heapgettup_pagemode(scan, direction,
scan->rs_base.rs_nkeys, scan->rs_base.rs_key);
else
heapgettup(scan, direction,
scan->rs_base.rs_nkeys, scan->rs_base.rs_key);
if (scan->rs_ctup.t_data == NULL)
{
HEAPDEBUG_2; /* heap_getnext returning EOS */
return NULL;
}
/*
* if we get here it means we have a new current scan tuple, so point to
* the proper return buffer and return the tuple.
*/
HEAPDEBUG_3; /* heap_getnext returning tuple */
pgstat_count_heap_getnext(scan->rs_base.rs_rd);
return &scan->rs_ctup;
}
#ifdef HEAPAMSLOTDEBUGALL
#define HEAPAMSLOTDEBUG_1 \
elog(DEBUG2, "heapam_getnextslot([%s,nkeys=%d],dir=%d) called", \
RelationGetRelationName(scan->rs_base.rs_rd), scan->rs_base.rs_nkeys, (int) direction)
#define HEAPAMSLOTDEBUG_2 \
elog(DEBUG2, "heapam_getnextslot returning EOS")
#define HEAPAMSLOTDEBUG_3 \
elog(DEBUG2, "heapam_getnextslot returning tuple")
#else
#define HEAPAMSLOTDEBUG_1
#define HEAPAMSLOTDEBUG_2
#define HEAPAMSLOTDEBUG_3
#endif
bool
heap_getnextslot(TableScanDesc sscan, ScanDirection direction, TupleTableSlot *slot)
{
HeapScanDesc scan = (HeapScanDesc) sscan;
/* Note: no locking manipulations needed */
HEAPAMSLOTDEBUG_1; /* heap_getnextslot( info ) */
if (sscan->rs_flags & SO_ALLOW_PAGEMODE)
heapgettup_pagemode(scan, direction, sscan->rs_nkeys, sscan->rs_key);
else
heapgettup(scan, direction, sscan->rs_nkeys, sscan->rs_key);
if (scan->rs_ctup.t_data == NULL)
{
HEAPAMSLOTDEBUG_2; /* heap_getnextslot returning EOS */
ExecClearTuple(slot);
return false;
}
/*
* if we get here it means we have a new current scan tuple, so point to
* the proper return buffer and return the tuple.
*/
HEAPAMSLOTDEBUG_3; /* heap_getnextslot returning tuple */
pgstat_count_heap_getnext(scan->rs_base.rs_rd);
ExecStoreBufferHeapTuple(&scan->rs_ctup, slot,
scan->rs_cbuf);
return true;
}
/*
* heap_fetch - retrieve tuple with given tid
*
* On entry, tuple->t_self is the TID to fetch. We pin the buffer holding
* the tuple, fill in the remaining fields of *tuple, and check the tuple
* against the specified snapshot.
*
* If successful (tuple found and passes snapshot time qual), then *userbuf
* is set to the buffer holding the tuple and true is returned. The caller
* must unpin the buffer when done with the tuple.
*
* If the tuple is not found (ie, item number references a deleted slot),
* then tuple->t_data is set to NULL and false is returned.
*
* If the tuple is found but fails the time qual check, then false is returned
* but tuple->t_data is left pointing to the tuple.
*
* heap_fetch does not follow HOT chains: only the exact TID requested will
* be fetched.
*
* It is somewhat inconsistent that we ereport() on invalid block number but
* return false on invalid item number. There are a couple of reasons though.
* One is that the caller can relatively easily check the block number for
* validity, but cannot check the item number without reading the page
* himself. Another is that when we are following a t_ctid link, we can be
* reasonably confident that the page number is valid (since VACUUM shouldn't
* truncate off the destination page without having killed the referencing
* tuple first), but the item number might well not be good.
*/
bool
heap_fetch(Relation relation,
Snapshot snapshot,
HeapTuple tuple,
Buffer *userbuf)
{
ItemPointer tid = &(tuple->t_self);
ItemId lp;
Buffer buffer;
Page page;
OffsetNumber offnum;
bool valid;
/*
* Fetch and pin the appropriate page of the relation.
*/
buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
/*
* Need share lock on buffer to examine tuple commit status.
*/
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
TestForOldSnapshot(snapshot, relation, page);
/*
* We'd better check for out-of-range offnum in case of VACUUM since the
* TID was obtained.
*/
offnum = ItemPointerGetOffsetNumber(tid);
if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(page))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
*userbuf = InvalidBuffer;
tuple->t_data = NULL;
return false;
}
/*
* get the item line pointer corresponding to the requested tid
*/
lp = PageGetItemId(page, offnum);
/*
* Must check for deleted tuple.
*/
if (!ItemIdIsNormal(lp))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
*userbuf = InvalidBuffer;
tuple->t_data = NULL;
return false;
}
/*
* fill in *tuple fields
*/
tuple->t_data = (HeapTupleHeader) PageGetItem(page, lp);
tuple->t_len = ItemIdGetLength(lp);
tuple->t_tableOid = RelationGetRelid(relation);
/*
* check tuple visibility, then release lock
*/
valid = HeapTupleSatisfiesVisibility(relation, tuple, snapshot, buffer);
if (valid)
PredicateLockTuple(relation, tuple, snapshot);
CheckForSerializableConflictOut(valid, relation, tuple, buffer, snapshot);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
if (valid)
{
/*
* All checks passed, so return the tuple as valid. Caller is now
* responsible for releasing the buffer.
*/
*userbuf = buffer;
return true;
}
/* Tuple failed time qual */
ReleaseBuffer(buffer);
*userbuf = InvalidBuffer;
return false;
}
/*
* heap_hot_search_buffer - search HOT chain for tuple satisfying snapshot
*
* On entry, *tid is the TID of a tuple (either a simple tuple, or the root
* of a HOT chain), and buffer is the buffer holding this tuple. We search
* for the first chain member satisfying the given snapshot. If one is
* found, we update *tid to reference that tuple's offset number, and
* return true. If no match, return false without modifying *tid.
*
* heapTuple is a caller-supplied buffer. When a match is found, we return
* the tuple here, in addition to updating *tid. If no match is found, the
* contents of this buffer on return are undefined.
*
* If all_dead is not NULL, we check non-visible tuples to see if they are
* globally dead; *all_dead is set true if all members of the HOT chain
* are vacuumable, false if not.
*
* Unlike heap_fetch, the caller must already have pin and (at least) share
* lock on the buffer; it is still pinned/locked at exit. Also unlike
* heap_fetch, we do not report any pgstats count; caller may do so if wanted.
*/
bool
heap_hot_search_buffer(ItemPointer tid, Relation relation, Buffer buffer,
Snapshot snapshot, HeapTuple heapTuple,
bool *all_dead, bool first_call)
{
Page dp = (Page) BufferGetPage(buffer);
TransactionId prev_xmax = InvalidTransactionId;
OffsetNumber offnum;
bool at_chain_start;
bool valid;
bool skip;
/* If this is not the first call, previous call returned a (live!) tuple */
if (all_dead)
*all_dead = first_call;
Assert(TransactionIdIsValid(RecentGlobalXmin));
Assert(ItemPointerGetBlockNumber(tid) == BufferGetBlockNumber(buffer));
offnum = ItemPointerGetOffsetNumber(tid);
at_chain_start = first_call;
skip = !first_call;
heapTuple->t_self = *tid;
/* Scan through possible multiple members of HOT-chain */
for (;;)
{
ItemId lp;
/* check for bogus TID */
if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(dp))
break;
lp = PageGetItemId(dp, offnum);
/* check for unused, dead, or redirected items */
if (!ItemIdIsNormal(lp))
{
/* We should only see a redirect at start of chain */
if (ItemIdIsRedirected(lp) && at_chain_start)
{
/* Follow the redirect */
offnum = ItemIdGetRedirect(lp);
at_chain_start = false;
continue;
}
/* else must be end of chain */
break;
}
heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
heapTuple->t_len = ItemIdGetLength(lp);
heapTuple->t_tableOid = RelationGetRelid(relation);
ItemPointerSetOffsetNumber(&heapTuple->t_self, offnum);
/*
* Shouldn't see a HEAP_ONLY tuple at chain start.
*/
if (at_chain_start && HeapTupleIsHeapOnly(heapTuple))
break;
/*
* The xmin should match the previous xmax value, else chain is
* broken.
*/
if (TransactionIdIsValid(prev_xmax) &&
!TransactionIdEquals(prev_xmax,
HeapTupleHeaderGetXmin(heapTuple->t_data)))
break;
/*
* When first_call is true (and thus, skip is initially false) we'll
* return the first tuple we find. But on later passes, heapTuple
* will initially be pointing to the tuple we returned last time.
* Returning it again would be incorrect (and would loop forever), so
* we skip it and return the next match we find.
*/
if (!skip)
{
/*
* For the benefit of logical decoding, have t_self point at the
* element of the HOT chain we're currently investigating instead
* of the root tuple of the HOT chain. This is important because
* the *Satisfies routine for historical mvcc snapshots needs the
* correct tid to decide about the visibility in some cases.
*/
ItemPointerSet(&(heapTuple->t_self), BufferGetBlockNumber(buffer), offnum);
/* If it's visible per the snapshot, we must return it */
valid = HeapTupleSatisfiesVisibility(relation, heapTuple, snapshot, buffer);
CheckForSerializableConflictOut(valid, relation, heapTuple,
buffer, snapshot);
/* reset to original, non-redirected, tid */
heapTuple->t_self = *tid;
if (valid)
{
ItemPointerSetOffsetNumber(tid, offnum);
PredicateLockTuple(relation, heapTuple, snapshot);
if (all_dead)
*all_dead = false;
return true;
}
}
skip = false;
/*
* If we can't see it, maybe no one else can either. At caller
* request, check whether all chain members are dead to all
* transactions.
*
* Note: if you change the criterion here for what is "dead", fix the
* planner's get_actual_variable_range() function to match.
*/
if (all_dead && *all_dead &&
!HeapTupleIsSurelyDead(heapTuple, RecentGlobalXmin))
*all_dead = false;
/*
* Check to see if HOT chain continues past this tuple; if so fetch
* the next offnum and loop around.
*/
if (HeapTupleIsHotUpdated(heapTuple))
{
Assert(ItemPointerGetBlockNumber(&heapTuple->t_data->t_ctid) ==
ItemPointerGetBlockNumber(tid));
offnum = ItemPointerGetOffsetNumber(&heapTuple->t_data->t_ctid);
at_chain_start = false;
prev_xmax = HeapTupleHeaderGetUpdateXid(heapTuple->t_data);
}
else
break; /* end of chain */
}
return false;
}
/*
* heap_get_latest_tid - get the latest tid of a specified tuple
*
* Actually, this gets the latest version that is visible according to the
* scan's snapshot. Create a scan using SnapshotDirty to get the very latest,
* possibly uncommitted version.
*
* *tid is both an input and an output parameter: it is updated to
* show the latest version of the row. Note that it will not be changed
* if no version of the row passes the snapshot test.
*/
void
heap_get_latest_tid(TableScanDesc sscan,
ItemPointer tid)
{
Relation relation = sscan->rs_rd;
Snapshot snapshot = sscan->rs_snapshot;
ItemPointerData ctid;
TransactionId priorXmax;
/*
* table_get_latest_tid verified that the passed in tid is valid. Assume
* that t_ctid links are valid however - there shouldn't be invalid ones
* in the table.
*/
Assert(ItemPointerIsValid(tid));
/*
* Loop to chase down t_ctid links. At top of loop, ctid is the tuple we
* need to examine, and *tid is the TID we will return if ctid turns out
* to be bogus.
*
* Note that we will loop until we reach the end of the t_ctid chain.
* Depending on the snapshot passed, there might be at most one visible
* version of the row, but we don't try to optimize for that.
*/
ctid = *tid;
priorXmax = InvalidTransactionId; /* cannot check first XMIN */
for (;;)
{
Buffer buffer;
Page page;
OffsetNumber offnum;
ItemId lp;
HeapTupleData tp;
bool valid;
/*
* Read, pin, and lock the page.
*/
buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&ctid));
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
TestForOldSnapshot(snapshot, relation, page);
/*
* Check for bogus item number. This is not treated as an error
* condition because it can happen while following a t_ctid link. We
* just assume that the prior tid is OK and return it unchanged.
*/
offnum = ItemPointerGetOffsetNumber(&ctid);
if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(page))
{
UnlockReleaseBuffer(buffer);
break;
}
lp = PageGetItemId(page, offnum);
if (!ItemIdIsNormal(lp))
{
UnlockReleaseBuffer(buffer);
break;
}
/* OK to access the tuple */
tp.t_self = ctid;
tp.t_data = (HeapTupleHeader) PageGetItem(page, lp);
tp.t_len = ItemIdGetLength(lp);
tp.t_tableOid = RelationGetRelid(relation);
/*
* After following a t_ctid link, we might arrive at an unrelated
* tuple. Check for XMIN match.
*/
if (TransactionIdIsValid(priorXmax) &&
!TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(tp.t_data)))
{
UnlockReleaseBuffer(buffer);
break;
}
/*
* Check tuple visibility; if visible, set it as the new result
* candidate.
*/
valid = HeapTupleSatisfiesVisibility(relation, &tp, snapshot, buffer);
CheckForSerializableConflictOut(valid, relation, &tp, buffer, snapshot);
if (valid)
*tid = ctid;
/*
* If there's a valid t_ctid link, follow it, else we're done.
*/
if ((tp.t_data->t_infomask & HEAP_XMAX_INVALID) ||
HeapTupleHeaderIsOnlyLocked(tp.t_data) ||
HeapTupleHeaderIndicatesMovedPartitions(tp.t_data) ||
ItemPointerEquals(&tp.t_self, &tp.t_data->t_ctid))
{
UnlockReleaseBuffer(buffer);
break;
}
ctid = tp.t_data->t_ctid;
priorXmax = HeapTupleHeaderGetUpdateXid(tp.t_data);
UnlockReleaseBuffer(buffer);
} /* end of loop */
}
/*
* UpdateXmaxHintBits - update tuple hint bits after xmax transaction ends
*
* This is called after we have waited for the XMAX transaction to terminate.
* If the transaction aborted, we guarantee the XMAX_INVALID hint bit will
* be set on exit. If the transaction committed, we set the XMAX_COMMITTED
* hint bit if possible --- but beware that that may not yet be possible,
* if the transaction committed asynchronously.
*
* Note that if the transaction was a locker only, we set HEAP_XMAX_INVALID
* even if it commits.
*
* Hence callers should look only at XMAX_INVALID.
*
* Note this is not allowed for tuples whose xmax is a multixact.
*/
static void
UpdateXmaxHintBits(HeapTupleHeader tuple, Buffer buffer, TransactionId xid, Relation rel)
{
Assert(TransactionIdEquals(HeapTupleHeaderGetRawXmax(tuple), xid));
Assert(!(tuple->t_infomask & HEAP_XMAX_IS_MULTI));
if (!(tuple->t_infomask & (HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID)))
{
if (!HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask) &&
TransactionIdDidCommit(xid))
HeapTupleSetHintBits(tuple, buffer, rel, HEAP_XMAX_COMMITTED,
xid);
else
HeapTupleSetHintBits(tuple, buffer, rel, HEAP_XMAX_INVALID,
InvalidTransactionId);
}
}
/*
* GetBulkInsertState - prepare status object for a bulk insert
*/
BulkInsertState
GetBulkInsertState(void)
{
BulkInsertState bistate;
bistate = (BulkInsertState) palloc(sizeof(BulkInsertStateData));
bistate->strategy = GetAccessStrategy(BAS_BULKWRITE);
bistate->current_buf = InvalidBuffer;
return bistate;
}
/*
* FreeBulkInsertState - clean up after finishing a bulk insert
*/
void
FreeBulkInsertState(BulkInsertState bistate)
{
if (bistate->current_buf != InvalidBuffer)
ReleaseBuffer(bistate->current_buf);
FreeAccessStrategy(bistate->strategy);
pfree(bistate);
}
/*
* ReleaseBulkInsertStatePin - release a buffer currently held in bistate
*/
void
ReleaseBulkInsertStatePin(BulkInsertState bistate)
{
if (bistate->current_buf != InvalidBuffer)
ReleaseBuffer(bistate->current_buf);
bistate->current_buf = InvalidBuffer;
}
/*
* heap_insert - insert tuple into a heap
*
* The new tuple is stamped with current transaction ID and the specified
* command ID.
*
* See table_tuple_insert for comments about most of the input flags, except
* that this routine directly takes a tuple rather than a slot.
*
* There's corresponding HEAP_INSERT_ options to all the TABLE_INSERT_
* options, and there additionally is HEAP_INSERT_SPECULATIVE which is used to
* implement table_tuple_insert_speculative().
*
* On return the header fields of *tup are updated to match the stored tuple;
* in particular tup->t_self receives the actual TID where the tuple was
* stored. But note that any toasting of fields within the tuple data is NOT
* reflected into *tup.
*/
void
heap_insert(Relation relation, HeapTuple tup, CommandId cid,
int options, BulkInsertState bistate, TransactionId xid)
{
bool isFrozen = (xid == FrozenTransactionId);
HeapTuple heaptup;
Buffer buffer;
Buffer vmbuffer = InvalidBuffer;
bool all_visible_cleared = false;
bool needwal;
needwal = !(options & HEAP_INSERT_SKIP_WAL) && RelationNeedsWAL(relation);
gp_expand_protect_catalog_changes(relation);
#ifdef FAULT_INJECTOR
FaultInjector_InjectFaultIfSet("heap_insert", DDLNotSpecified, "",
RelationGetRelationName(relation));
#endif
/*
* Fill in tuple header fields and toast the tuple if necessary.
*
* Note: below this point, heaptup is the data we actually intend to store
* into the relation; tup is the caller's original untoasted data.
*/
heaptup = heap_prepare_insert(relation, tup, xid, cid, options, isFrozen);
/*
* Find buffer to insert this tuple into. If the page is all visible,
* this will also pin the requisite visibility map page.
*/
buffer = RelationGetBufferForTuple(relation, heaptup->t_len,
InvalidBuffer, options, bistate,
&vmbuffer, NULL);
/*
* We're about to do the actual insert -- but check for conflict first, to
* avoid possibly having to roll back work we've just done.
*
* This is safe without a recheck as long as there is no possibility of
* another process scanning the page between this check and the insert
* being visible to the scan (i.e., an exclusive buffer content lock is
* continuously held from this point until the tuple insert is visible).
*
* For a heap insert, we only need to check for table-level SSI locks. Our
* new tuple can't possibly conflict with existing tuple locks, and heap
* page locks are only consolidated versions of tuple locks; they do not
* lock "gaps" as index page locks do. So we don't need to specify a
* buffer when making the call, which makes for a faster check.
*/
CheckForSerializableConflictIn(relation, NULL, InvalidBuffer);
/* NO EREPORT(ERROR) from here till changes are logged */
START_CRIT_SECTION();
RelationPutHeapTuple(relation, buffer, heaptup,
(options & HEAP_INSERT_SPECULATIVE) != 0);
if (PageIsAllVisible(BufferGetPage(buffer)))
{
all_visible_cleared = true;
PageClearAllVisible(BufferGetPage(buffer));
visibilitymap_clear(relation,
ItemPointerGetBlockNumber(&(heaptup->t_self)),
vmbuffer, VISIBILITYMAP_VALID_BITS);
}
/*
* XXX Should we set PageSetPrunable on this page ?
*
* The inserting transaction may eventually abort thus making this tuple
* DEAD and hence available for pruning. Though we don't want to optimize
* for aborts, if no other tuple in this page is UPDATEd/DELETEd, the
* aborted tuple will never be pruned until next vacuum is triggered.
*
* If you do add PageSetPrunable here, add it in heap_xlog_insert too.
*/
MarkBufferDirty(buffer);
/* XLOG stuff */
if (needwal)
{
xl_heap_insert xlrec;
xl_heap_header xlhdr;
XLogRecPtr recptr;
Page page = BufferGetPage(buffer);
uint8 info = XLOG_HEAP_INSERT;
int bufflags = 0;
/*
* If this is a catalog, we need to transmit combocids to properly
* decode, so log that as well.
*/
if (RelationIsAccessibleInLogicalDecoding(relation))
log_heap_new_cid(relation, heaptup);
/*
* If this is the single and first tuple on page, we can reinit the
* page instead of restoring the whole thing. Set flag, and hide
* buffer references from XLogInsert.
*/
if (ItemPointerGetOffsetNumber(&(heaptup->t_self)) == FirstOffsetNumber &&
PageGetMaxOffsetNumber(page) == FirstOffsetNumber)
{
info |= XLOG_HEAP_INIT_PAGE;
bufflags |= REGBUF_WILL_INIT;
}
xlrec.offnum = ItemPointerGetOffsetNumber(&heaptup->t_self);
xlrec.flags = 0;
if (all_visible_cleared)
xlrec.flags |= XLH_INSERT_ALL_VISIBLE_CLEARED;
if (options & HEAP_INSERT_SPECULATIVE)
xlrec.flags |= XLH_INSERT_IS_SPECULATIVE;
Assert(ItemPointerGetBlockNumber(&heaptup->t_self) == BufferGetBlockNumber(buffer));
/*
* For logical decoding, we need the tuple even if we're doing a full
* page write, so make sure it's included even if we take a full-page
* image. (XXX We could alternatively store a pointer into the FPW).
*/
if (RelationIsLogicallyLogged(relation) &&
!(options & HEAP_INSERT_NO_LOGICAL))
{
xlrec.flags |= XLH_INSERT_CONTAINS_NEW_TUPLE;
bufflags |= REGBUF_KEEP_DATA;
}
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapInsert);
xlhdr.t_infomask2 = heaptup->t_data->t_infomask2;
xlhdr.t_infomask = heaptup->t_data->t_infomask;
xlhdr.t_hoff = heaptup->t_data->t_hoff;
/*
* note we mark xlhdr as belonging to buffer; if XLogInsert decides to
* write the whole page to the xlog, we don't need to store
* xl_heap_header in the xlog.
*/
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD | bufflags);
XLogRegisterBufData(0, (char *) &xlhdr, SizeOfHeapHeader);
/* PG73FORMAT: write bitmap [+ padding] [+ oid] + data */
XLogRegisterBufData(0,
(char *) heaptup->t_data + SizeofHeapTupleHeader,
heaptup->t_len - SizeofHeapTupleHeader);
/* filtering by origin on a row level is much more efficient */
XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN);
if (!isFrozen)
recptr = XLogInsert(RM_HEAP_ID, info);
else
recptr = XLogInsert_OverrideXid(RM_HEAP_ID, info, FrozenTransactionId);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
UnlockReleaseBuffer(buffer);
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
/*
* If tuple is cachable, mark it for invalidation from the caches in case
* we abort. Note it is OK to do this after releasing the buffer, because
* the heaptup data structure is all in local memory, not in the shared
* buffer.
*/
if (IsSystemRelation(relation))
CacheInvalidateHeapTuple(relation, heaptup, NULL);
/* Note: speculative insertions are counted too, even if aborted later */
pgstat_count_heap_insert(relation, 1);
/*
* If heaptup is a private copy, release it. Don't forget to copy t_self
* back to the caller's image, too.
*/
if (heaptup != tup)
{
tup->t_self = heaptup->t_self;
heap_freetuple(heaptup);
}
if (needwal)
wait_to_avoid_large_repl_lag();
}
/*
* Subroutine for heap_insert(). Prepares a tuple for insertion. This sets the
* tuple header fields and toasts the tuple if necessary. Returns a toasted
* version of the tuple if it was toasted, or the original tuple if not. Note
* that in any case, the header fields are also set in the original tuple.
*/
static HeapTuple
heap_prepare_insert(Relation relation, HeapTuple tup, TransactionId xid,
CommandId cid, int options, bool isFrozen)
{
/*
* Parallel operations are required to be strictly read-only in a parallel
* worker. Parallel inserts are not safe even in the leader in the
* general case, because group locking means that heavyweight locks for
* relation extension or GIN page locks will not conflict between members
* of a lock group, but we don't prohibit that case here because there are
* useful special cases that we can safely allow, such as CREATE TABLE AS.
*/
if (IsParallelWorker())
ereport(ERROR,
(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
errmsg("cannot insert tuples in a parallel worker")));
tup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
if (isFrozen)
tup->t_data->t_infomask |= HEAP_XMIN_COMMITTED;
tup->t_data->t_infomask2 &= ~(HEAP2_XACT_MASK);
tup->t_data->t_infomask |= HEAP_XMAX_INVALID;
HeapTupleHeaderSetXmin(tup->t_data, xid);
if (options & HEAP_INSERT_FROZEN)
HeapTupleHeaderSetXminFrozen(tup->t_data);
HeapTupleHeaderSetCmin(tup->t_data, cid);
HeapTupleHeaderSetXmax(tup->t_data, 0); /* for cleanliness */
tup->t_tableOid = RelationGetRelid(relation);
/*
* If the new tuple is too big for storage or contains already toasted
* out-of-line attributes from some other relation, invoke the toaster.
*/
if (relation->rd_rel->relkind != RELKIND_RELATION &&
relation->rd_rel->relkind != RELKIND_MATVIEW)
{
/* toast table entries should never be recursively toasted */
Assert(!HeapTupleHasExternal(tup));
return tup;
}
else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD)
return toast_insert_or_update(relation, tup, NULL,
TOAST_TUPLE_TARGET, isFrozen,
options);
else
return tup;
}
/*
* heap_multi_insert - insert multiple tuple into a heap
*
* This is like heap_insert(), but inserts multiple tuples in one operation.
* That's faster than calling heap_insert() in a loop, because when multiple
* tuples can be inserted on a single page, we can write just a single WAL
* record covering all of them, and only need to lock/unlock the page once.
*
* Note: this leaks memory into the current memory context. You can create a
* temporary context before calling this, if that's a problem.
*/
void
heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
CommandId cid, int options, BulkInsertState bistate)
{
TransactionId xid = GetCurrentTransactionId();
bool isFrozen = false;
HeapTuple *heaptuples;
int i;
int ndone;
PGAlignedBlock scratch;
Page page;
bool needwal;
Size saveFreeSpace;
bool need_tuple_data = RelationIsLogicallyLogged(relation);
bool need_cids = RelationIsAccessibleInLogicalDecoding(relation);
/* currently not needed (thus unsupported) for heap_multi_insert() */
AssertArg(!(options & HEAP_INSERT_NO_LOGICAL));
needwal = !(options & HEAP_INSERT_SKIP_WAL) && RelationNeedsWAL(relation);
saveFreeSpace = RelationGetTargetPageFreeSpace(relation,
HEAP_DEFAULT_FILLFACTOR);
/* Toast and set header data in all the slots */
heaptuples = palloc(ntuples * sizeof(HeapTuple));
for (i = 0; i < ntuples; i++)
{
HeapTuple tuple;
tuple = ExecFetchSlotHeapTuple(slots[i], true, NULL);
slots[i]->tts_tableOid = RelationGetRelid(relation);
tuple->t_tableOid = slots[i]->tts_tableOid;
heaptuples[i] = heap_prepare_insert(relation, tuple, xid, cid,
options, isFrozen);
}
/*
* We're about to do the actual inserts -- but check for conflict first,
* to minimize the possibility of having to roll back work we've just
* done.
*
* A check here does not definitively prevent a serialization anomaly;
* that check MUST be done at least past the point of acquiring an
* exclusive buffer content lock on every buffer that will be affected,
* and MAY be done after all inserts are reflected in the buffers and
* those locks are released; otherwise there race condition. Since
* multiple buffers can be locked and unlocked in the loop below, and it
* would not be feasible to identify and lock all of those buffers before
* the loop, we must do a final check at the end.
*
* The check here could be omitted with no loss of correctness; it is
* present strictly as an optimization.
*
* For heap inserts, we only need to check for table-level SSI locks. Our
* new tuples can't possibly conflict with existing tuple locks, and heap
* page locks are only consolidated versions of tuple locks; they do not
* lock "gaps" as index page locks do. So we don't need to specify a
* buffer when making the call, which makes for a faster check.
*/
CheckForSerializableConflictIn(relation, NULL, InvalidBuffer);
ndone = 0;
while (ndone < ntuples)
{
Buffer buffer;
Buffer vmbuffer = InvalidBuffer;
bool all_visible_cleared = false;
int nthispage;
CHECK_FOR_INTERRUPTS();
/*
* Find buffer where at least the next tuple will fit. If the page is
* all-visible, this will also pin the requisite visibility map page.
*/
buffer = RelationGetBufferForTuple(relation, heaptuples[ndone]->t_len,
InvalidBuffer, options, bistate,
&vmbuffer, NULL);
page = BufferGetPage(buffer);
/* NO EREPORT(ERROR) from here till changes are logged */
START_CRIT_SECTION();
/*
* RelationGetBufferForTuple has ensured that the first tuple fits.
* Put that on the page, and then as many other tuples as fit.
*/
RelationPutHeapTuple(relation, buffer, heaptuples[ndone], false);
for (nthispage = 1; ndone + nthispage < ntuples; nthispage++)
{
HeapTuple heaptup = heaptuples[ndone + nthispage];
if (PageGetHeapFreeSpace(page) < MAXALIGN(heaptup->t_len) + saveFreeSpace)
break;
RelationPutHeapTuple(relation, buffer, heaptup, false);
/*
* We don't use heap_multi_insert for catalog tuples yet, but
* better be prepared...
*/
if (needwal && need_cids)
log_heap_new_cid(relation, heaptup);
}
if (PageIsAllVisible(page))
{
all_visible_cleared = true;
PageClearAllVisible(page);
visibilitymap_clear(relation,
BufferGetBlockNumber(buffer),
vmbuffer, VISIBILITYMAP_VALID_BITS);
}
/*
* XXX Should we set PageSetPrunable on this page ? See heap_insert()
*/
MarkBufferDirty(buffer);
/* XLOG stuff */
if (needwal)
{
XLogRecPtr recptr;
xl_heap_multi_insert *xlrec;
uint8 info = XLOG_HEAP2_MULTI_INSERT;
char *tupledata;
int totaldatalen;
char *scratchptr = scratch.data;
bool init;
int bufflags = 0;
/*
* If the page was previously empty, we can reinit the page
* instead of restoring the whole thing.
*/
init = (ItemPointerGetOffsetNumber(&(heaptuples[ndone]->t_self)) == FirstOffsetNumber &&
PageGetMaxOffsetNumber(page) == FirstOffsetNumber + nthispage - 1);
/* allocate xl_heap_multi_insert struct from the scratch area */
xlrec = (xl_heap_multi_insert *) scratchptr;
scratchptr += SizeOfHeapMultiInsert;
/*
* Allocate offsets array. Unless we're reinitializing the page,
* in that case the tuples are stored in order starting at
* FirstOffsetNumber and we don't need to store the offsets
* explicitly.
*/
if (!init)
scratchptr += nthispage * sizeof(OffsetNumber);
/* the rest of the scratch space is used for tuple data */
tupledata = scratchptr;
xlrec->flags = all_visible_cleared ? XLH_INSERT_ALL_VISIBLE_CLEARED : 0;
xlrec->ntuples = nthispage;
/*
* Write out an xl_multi_insert_tuple and the tuple data itself
* for each tuple.
*/
for (i = 0; i < nthispage; i++)
{
HeapTuple heaptup = heaptuples[ndone + i];
xl_multi_insert_tuple *tuphdr;
int datalen;
if (!init)
xlrec->offsets[i] = ItemPointerGetOffsetNumber(&heaptup->t_self);
/* xl_multi_insert_tuple needs two-byte alignment. */
tuphdr = (xl_multi_insert_tuple *) SHORTALIGN(scratchptr);
scratchptr = ((char *) tuphdr) + SizeOfMultiInsertTuple;
tuphdr->t_infomask2 = heaptup->t_data->t_infomask2;
tuphdr->t_infomask = heaptup->t_data->t_infomask;
tuphdr->t_hoff = heaptup->t_data->t_hoff;
/* write bitmap [+ padding] [+ oid] + data */
datalen = heaptup->t_len - SizeofHeapTupleHeader;
memcpy(scratchptr,
(char *) heaptup->t_data + SizeofHeapTupleHeader,
datalen);
tuphdr->datalen = datalen;
scratchptr += datalen;
}
totaldatalen = scratchptr - tupledata;
Assert((scratchptr - scratch.data) < BLCKSZ);
if (need_tuple_data)
xlrec->flags |= XLH_INSERT_CONTAINS_NEW_TUPLE;
/*
* Signal that this is the last xl_heap_multi_insert record
* emitted by this call to heap_multi_insert(). Needed for logical
* decoding so it knows when to cleanup temporary data.
*/
if (ndone + nthispage == ntuples)
xlrec->flags |= XLH_INSERT_LAST_IN_MULTI;
if (init)
{
info |= XLOG_HEAP_INIT_PAGE;
bufflags |= REGBUF_WILL_INIT;
}
/*
* If we're doing logical decoding, include the new tuple data
* even if we take a full-page image of the page.
*/
if (need_tuple_data)
bufflags |= REGBUF_KEEP_DATA;
XLogBeginInsert();
XLogRegisterData((char *) xlrec, tupledata - scratch.data);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD | bufflags);
XLogRegisterBufData(0, tupledata, totaldatalen);
/* filtering by origin on a row level is much more efficient */
XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN);
recptr = XLogInsert(RM_HEAP2_ID, info);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
UnlockReleaseBuffer(buffer);
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
ndone += nthispage;
}
/*
* We're done with the actual inserts. Check for conflicts again, to
* ensure that all rw-conflicts in to these inserts are detected. Without
* this final check, a sequential scan of the heap may have locked the
* table after the "before" check, missing one opportunity to detect the
* conflict, and then scanned the table before the new tuples were there,
* missing the other chance to detect the conflict.
*
* For heap inserts, we only need to check for table-level SSI locks. Our
* new tuples can't possibly conflict with existing tuple locks, and heap
* page locks are only consolidated versions of tuple locks; they do not
* lock "gaps" as index page locks do. So we don't need to specify a
* buffer when making the call.
*/
CheckForSerializableConflictIn(relation, NULL, InvalidBuffer);
/*
* If tuples are cachable, mark them for invalidation from the caches in
* case we abort. Note it is OK to do this after releasing the buffer,
* because the heaptuples data structure is all in local memory, not in
* the shared buffer.
*/
if (IsCatalogRelation(relation))
{
for (i = 0; i < ntuples; i++)
CacheInvalidateHeapTuple(relation, heaptuples[i], NULL);
}
/* copy t_self fields back to the caller's slots */
for (i = 0; i < ntuples; i++)
slots[i]->tts_tid = heaptuples[i]->t_self;
pgstat_count_heap_insert(relation, ntuples);
if (needwal)
wait_to_avoid_large_repl_lag();
}
/*
* simple_heap_insert - insert a tuple
*
* Currently, this routine differs from heap_insert only in supplying
* a default command ID and not allowing access to the speedup options.
*
* This should be used rather than using heap_insert directly in most places
* where we are modifying system catalogs.
*/
void
simple_heap_insert(Relation relation, HeapTuple tup)
{
heap_insert(relation, tup, GetCurrentCommandId(true), 0, NULL,
GetCurrentTransactionId());
}
/*
* frozen_heap_insert - insert a tuple and freeze it (always visible).
*
* Currently, this routine differs from heap_insert in supplying
* a default command ID and a frozen transaction id. Also, the committed
* bit of the tuple is set. This function is currently used for data that
* goes into error tables and need to stay there even if transaction
* aborts.
*/
void
frozen_heap_insert(Relation relation, HeapTuple tup)
{
return heap_insert(relation, tup, GetCurrentCommandId(true),
0, NULL, FrozenTransactionId);
}
/*
* Given infomask/infomask2, compute the bits that must be saved in the
* "infobits" field of xl_heap_delete, xl_heap_update, xl_heap_lock,
* xl_heap_lock_updated WAL records.
*
* See fix_infomask_from_infobits.
*/
static uint8
compute_infobits(uint16 infomask, uint16 infomask2)
{
return
((infomask & HEAP_XMAX_IS_MULTI) != 0 ? XLHL_XMAX_IS_MULTI : 0) |
((infomask & HEAP_XMAX_LOCK_ONLY) != 0 ? XLHL_XMAX_LOCK_ONLY : 0) |
((infomask & HEAP_XMAX_EXCL_LOCK) != 0 ? XLHL_XMAX_EXCL_LOCK : 0) |
/* note we ignore HEAP_XMAX_SHR_LOCK here */
((infomask & HEAP_XMAX_KEYSHR_LOCK) != 0 ? XLHL_XMAX_KEYSHR_LOCK : 0) |
((infomask2 & HEAP_KEYS_UPDATED) != 0 ?
XLHL_KEYS_UPDATED : 0);
}
/*
* Given two versions of the same t_infomask for a tuple, compare them and
* return whether the relevant status for a tuple Xmax has changed. This is
* used after a buffer lock has been released and reacquired: we want to ensure
* that the tuple state continues to be the same it was when we previously
* examined it.
*
* Note the Xmax field itself must be compared separately.
*/
static inline bool
xmax_infomask_changed(uint16 new_infomask, uint16 old_infomask)
{
const uint16 interesting =
HEAP_XMAX_IS_MULTI | HEAP_XMAX_LOCK_ONLY | HEAP_LOCK_MASK;
if ((new_infomask & interesting) != (old_infomask & interesting))
return true;
return false;
}
/*
* heap_delete - delete a tuple
*
* See table_tuple_delete() for an explanation of the parameters, except that
* this routine directly takes a tuple rather than a slot.
*
* In the failure cases, the routine fills *tmfd with the tuple's t_ctid,
* t_xmax (resolving a possible MultiXact, if necessary), and t_cmax (the last
* only for TM_SelfModified, since we cannot obtain cmax from a combocid
* generated by another transaction).
*/
TM_Result
heap_delete(Relation relation, ItemPointer tid,
CommandId cid, Snapshot crosscheck, bool wait,
TM_FailureData *tmfd, bool changingPart)
{
TM_Result result;
TransactionId xid = GetCurrentTransactionId();
ItemId lp;
HeapTupleData tp;
Page page;
BlockNumber block;
Buffer buffer;
Buffer vmbuffer = InvalidBuffer;
TransactionId new_xmax;
uint16 new_infomask,
new_infomask2;
bool have_tuple_lock = false;
bool iscombo;
bool all_visible_cleared = false;
HeapTuple old_key_tuple = NULL; /* replica identity of the tuple */
bool old_key_copied = false;
Assert(ItemPointerIsValid(tid));
gp_expand_protect_catalog_changes(relation);
/*
* Forbid this during a parallel operation, lest it allocate a combocid.
* Other workers might need that combocid for visibility checks, and we
* have no provision for broadcasting it to them.
*/
if (IsInParallelMode())
ereport(ERROR,
(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
errmsg("cannot delete tuples during a parallel operation")));
block = ItemPointerGetBlockNumber(tid);
buffer = ReadBuffer(relation, block);
page = BufferGetPage(buffer);
/*
* Before locking the buffer, pin the visibility map page if it appears to
* be necessary. Since we haven't got the lock yet, someone else might be
* in the middle of changing this, so we'll need to recheck after we have
* the lock.
*/
if (PageIsAllVisible(page))
visibilitymap_pin(relation, block, &vmbuffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* If we didn't pin the visibility map page and the page has become all
* visible while we were busy locking the buffer, we'll have to unlock and
* re-lock, to avoid holding the buffer lock across an I/O. That's a bit
* unfortunate, but hopefully shouldn't happen often.
*/
if (vmbuffer == InvalidBuffer && PageIsAllVisible(page))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
visibilitymap_pin(relation, block, &vmbuffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
}
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid));
Assert(ItemIdIsNormal(lp));
tp.t_tableOid = RelationGetRelid(relation);
tp.t_data = (HeapTupleHeader) PageGetItem(page, lp);
tp.t_len = ItemIdGetLength(lp);
tp.t_self = *tid;
l1:
result = HeapTupleSatisfiesUpdate(relation, &tp, cid, buffer);
if (result == TM_Invisible)
{
UnlockReleaseBuffer(buffer);
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("attempted to delete invisible tuple")));
}
else if (result == TM_BeingModified && wait)
{
TransactionId xwait;
uint16 infomask;
/* must copy state data before unlocking buffer */
xwait = HeapTupleHeaderGetRawXmax(tp.t_data);
infomask = tp.t_data->t_infomask;
/*
* Sleep until concurrent transaction ends -- except when there's a
* single locker and it's our own transaction. Note we don't care
* which lock mode the locker has, because we need the strongest one.
*
* Before sleeping, we need to acquire tuple lock to establish our
* priority for the tuple (see heap_lock_tuple). LockTuple will
* release us when we are next-in-line for the tuple.
*
* If we are forced to "start over" below, we keep the tuple lock;
* this arranges that we stay at the head of the line while rechecking
* tuple state.
*/
if (infomask & HEAP_XMAX_IS_MULTI)
{
bool current_is_member = false;
if (DoesMultiXactIdConflict((MultiXactId) xwait, infomask,
LockTupleExclusive, ¤t_is_member))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/*
* Acquire the lock, if necessary (but skip it when we're
* requesting a lock and already have one; avoids deadlock).
*/
if (!current_is_member)
heap_acquire_tuplock(relation, &(tp.t_self), LockTupleExclusive,
LockWaitBlock, &have_tuple_lock);
/* wait for multixact */
MultiXactIdWait((MultiXactId) xwait, MultiXactStatusUpdate, infomask,
relation, &(tp.t_self), XLTW_Delete,
NULL);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* If xwait had just locked the tuple then some other xact
* could update this tuple before we get to this point. Check
* for xmax change, and start over if so.
*/
if (xmax_infomask_changed(tp.t_data->t_infomask, infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(tp.t_data),
xwait))
goto l1;
}
/*
* You might think the multixact is necessarily done here, but not
* so: it could have surviving members, namely our own xact or
* other subxacts of this backend. It is legal for us to delete
* the tuple in either case, however (the latter case is
* essentially a situation of upgrading our former shared lock to
* exclusive). We don't bother changing the on-disk hint bits
* since we are about to overwrite the xmax altogether.
*/
}
else if (!TransactionIdIsCurrentTransactionId(xwait))
{
/*
* Wait for regular transaction to end; but first, acquire tuple
* lock.
*/
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
heap_acquire_tuplock(relation, &(tp.t_self), LockTupleExclusive,
LockWaitBlock, &have_tuple_lock);
XactLockTableWait(xwait, relation, &(tp.t_self), XLTW_Delete);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* xwait is done, but if xwait had just locked the tuple then some
* other xact could update this tuple before we get to this point.
* Check for xmax change, and start over if so.
*/
if (xmax_infomask_changed(tp.t_data->t_infomask, infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(tp.t_data),
xwait))
goto l1;
/* Otherwise check if it committed or aborted */
UpdateXmaxHintBits(tp.t_data, buffer, xwait, relation);
}
/*
* We may overwrite if previous xmax aborted, or if it committed but
* only locked the tuple without updating it.
*/
if ((tp.t_data->t_infomask & HEAP_XMAX_INVALID) ||
HEAP_XMAX_IS_LOCKED_ONLY(tp.t_data->t_infomask) ||
HeapTupleHeaderIsOnlyLocked(tp.t_data))
result = TM_Ok;
else if (!ItemPointerEquals(&tp.t_self, &tp.t_data->t_ctid) ||
HeapTupleHeaderIndicatesMovedPartitions(tp.t_data))
result = TM_Updated;
else
result = TM_Deleted;
}
if (crosscheck != InvalidSnapshot && result == TM_Ok)
{
/* Perform additional check for transaction-snapshot mode RI updates */
if (!HeapTupleSatisfiesVisibility(relation, &tp, crosscheck, buffer))
result = TM_Updated;
}
if (result != TM_Ok)
{
Assert(result == TM_SelfModified ||
result == TM_Updated ||
result == TM_Deleted ||
result == TM_BeingModified);
Assert(!(tp.t_data->t_infomask & HEAP_XMAX_INVALID));
Assert(result != TM_Updated ||
!ItemPointerEquals(&tp.t_self, &tp.t_data->t_ctid));
tmfd->ctid = tp.t_data->t_ctid;
tmfd->xmax = HeapTupleHeaderGetUpdateXid(tp.t_data);
if (result == TM_SelfModified)
tmfd->cmax = HeapTupleHeaderGetCmax(tp.t_data);
else
tmfd->cmax = InvalidCommandId;
UnlockReleaseBuffer(buffer);
if (have_tuple_lock)
UnlockTupleTuplock(relation, &(tp.t_self), LockTupleExclusive);
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
return result;
}
/*
* We're about to do the actual delete -- check for conflict first, to
* avoid possibly having to roll back work we've just done.
*
* This is safe without a recheck as long as there is no possibility of
* another process scanning the page between this check and the delete
* being visible to the scan (i.e., an exclusive buffer content lock is
* continuously held from this point until the tuple delete is visible).
*/
CheckForSerializableConflictIn(relation, &tp, buffer);
/* replace cid with a combo cid if necessary */
HeapTupleHeaderAdjustCmax(tp.t_data, &cid, &iscombo);
/*
* Compute replica identity tuple before entering the critical section so
* we don't PANIC upon a memory allocation failure.
*/
old_key_tuple = ExtractReplicaIdentity(relation, &tp, true, &old_key_copied);
/*
* If this is the first possibly-multixact-able operation in the current
* transaction, set my per-backend OldestMemberMXactId setting. We can be
* certain that the transaction will never become a member of any older
* MultiXactIds than that. (We have to do this even if we end up just
* using our own TransactionId below, since some other backend could
* incorporate our XID into a MultiXact immediately afterwards.)
*/
MultiXactIdSetOldestMember();
compute_new_xmax_infomask(HeapTupleHeaderGetRawXmax(tp.t_data),
tp.t_data->t_infomask, tp.t_data->t_infomask2,
xid, LockTupleExclusive, true,
&new_xmax, &new_infomask, &new_infomask2);
START_CRIT_SECTION();
/*
* If this transaction commits, the tuple will become DEAD sooner or
* later. Set flag that this page is a candidate for pruning once our xid
* falls below the OldestXmin horizon. If the transaction finally aborts,
* the subsequent page pruning will be a no-op and the hint will be
* cleared.
*/
PageSetPrunable(page, xid);
if (PageIsAllVisible(page))
{
all_visible_cleared = true;
PageClearAllVisible(page);
visibilitymap_clear(relation, BufferGetBlockNumber(buffer),
vmbuffer, VISIBILITYMAP_VALID_BITS);
}
/* store transaction information of xact deleting the tuple */
tp.t_data->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
tp.t_data->t_infomask2 &= ~HEAP_KEYS_UPDATED;
tp.t_data->t_infomask |= new_infomask;
tp.t_data->t_infomask2 |= new_infomask2;
HeapTupleHeaderClearHotUpdated(tp.t_data);
HeapTupleHeaderSetXmax(tp.t_data, new_xmax);
HeapTupleHeaderSetCmax(tp.t_data, cid, iscombo);
/* Make sure there is no forward chain link in t_ctid */
tp.t_data->t_ctid = tp.t_self;
/* Signal that this is actually a move into another partition */
if (changingPart)
HeapTupleHeaderSetMovedPartitions(tp.t_data);
MarkBufferDirty(buffer);
/*
* XLOG stuff
*
* NB: heap_abort_speculative() uses the same xlog record and replay
* routines.
*/
if (RelationNeedsWAL(relation))
{
xl_heap_delete xlrec;
xl_heap_header xlhdr;
XLogRecPtr recptr;
/* For logical decode we need combocids to properly decode the catalog */
if (RelationIsAccessibleInLogicalDecoding(relation))
log_heap_new_cid(relation, &tp);
xlrec.flags = 0;
if (all_visible_cleared)
xlrec.flags |= XLH_DELETE_ALL_VISIBLE_CLEARED;
if (changingPart)
xlrec.flags |= XLH_DELETE_IS_PARTITION_MOVE;
xlrec.infobits_set = compute_infobits(tp.t_data->t_infomask,
tp.t_data->t_infomask2);
xlrec.offnum = ItemPointerGetOffsetNumber(&tp.t_self);
xlrec.xmax = new_xmax;
if (old_key_tuple != NULL)
{
if (relation->rd_rel->relreplident == REPLICA_IDENTITY_FULL)
xlrec.flags |= XLH_DELETE_CONTAINS_OLD_TUPLE;
else
xlrec.flags |= XLH_DELETE_CONTAINS_OLD_KEY;
}
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapDelete);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
/*
* Log replica identity of the deleted tuple if there is one
*/
if (old_key_tuple != NULL)
{
xlhdr.t_infomask2 = old_key_tuple->t_data->t_infomask2;
xlhdr.t_infomask = old_key_tuple->t_data->t_infomask;
xlhdr.t_hoff = old_key_tuple->t_data->t_hoff;
XLogRegisterData((char *) &xlhdr, SizeOfHeapHeader);
XLogRegisterData((char *) old_key_tuple->t_data
+ SizeofHeapTupleHeader,
old_key_tuple->t_len
- SizeofHeapTupleHeader);
}
/* filtering by origin on a row level is much more efficient */
XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN);
recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_DELETE);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
/*
* If the tuple has toasted out-of-line attributes, we need to delete
* those items too. We have to do this before releasing the buffer
* because we need to look at the contents of the tuple, but it's OK to
* release the content lock on the buffer first.
*/
if (relation->rd_rel->relkind != RELKIND_RELATION &&
relation->rd_rel->relkind != RELKIND_MATVIEW)
{
/* toast table entries should never be recursively toasted */
Assert(!HeapTupleHasExternal(&tp));
}
else if (HeapTupleHasExternal(&tp))
toast_delete(relation, &tp, false);
/*
* Mark tuple for invalidation from system caches at next command
* boundary. We have to do this before releasing the buffer because we
* need to look at the contents of the tuple.
*/
CacheInvalidateHeapTuple(relation, &tp, NULL);
/* Now we can release the buffer */
ReleaseBuffer(buffer);
/*
* Release the lmgr tuple lock, if we had it.
*/
if (have_tuple_lock)
UnlockTupleTuplock(relation, &(tp.t_self), LockTupleExclusive);
pgstat_count_heap_delete(relation);
if (old_key_tuple != NULL && old_key_copied)
heap_freetuple(old_key_tuple);
return TM_Ok;
}
/*
* simple_heap_delete - delete a tuple
*
* This routine may be used to delete a tuple when concurrent updates of
* the target tuple are not expected (for example, because we have a lock
* on the relation associated with the tuple). Any failure is reported
* via ereport().
*/
void
simple_heap_delete(Relation relation, ItemPointer tid)
{
TM_Result result;
TM_FailureData tmfd;
result = heap_delete(relation, tid,
GetCurrentCommandId(true), InvalidSnapshot,
true /* wait for commit */ ,
&tmfd, false /* changingPart */ );
switch (result)
{
case TM_SelfModified:
/* Tuple was already updated in current command? */
elog(ERROR, "tuple already updated by self");
break;
case TM_Ok:
/* done successfully */
break;
case TM_Updated:
elog(ERROR, "tuple concurrently updated");
break;
case TM_Deleted:
elog(ERROR, "tuple concurrently deleted");
break;
default:
elog(ERROR, "unrecognized heap_delete status: %u", result);
break;
}
}
/*
* heap_update - replace a tuple
*
* See table_tuple_update() for an explanation of the parameters, except that
* this routine directly takes a tuple rather than a slot.
*
* In the failure cases, the routine fills *tmfd with the tuple's t_ctid,
* t_xmax (resolving a possible MultiXact, if necessary), and t_cmax (the last
* only for TM_SelfModified, since we cannot obtain cmax from a combocid
* generated by another transaction).
*/
static TM_Result
heap_update_internal(Relation relation, ItemPointer otid, HeapTuple newtup,
CommandId cid, Snapshot crosscheck, bool wait,
TM_FailureData *tmfd, LockTupleMode *lockmode, bool simple)
{
TM_Result result;
TransactionId xid = GetCurrentTransactionId();
Bitmapset *hot_attrs;
Bitmapset *key_attrs;
Bitmapset *id_attrs;
Bitmapset *interesting_attrs;
Bitmapset *modified_attrs;
ItemId lp;
HeapTupleData oldtup;
HeapTuple heaptup;
HeapTuple old_key_tuple = NULL;
bool old_key_copied = false;
Page page;
BlockNumber block;
MultiXactStatus mxact_status;
Buffer buffer,
newbuf,
vmbuffer = InvalidBuffer,
vmbuffer_new = InvalidBuffer;
bool need_toast;
Size newtupsize,
pagefree;
bool have_tuple_lock = false;
bool iscombo;
bool use_hot_update = false;
bool hot_attrs_checked = false;
bool key_intact;
bool all_visible_cleared = false;
bool all_visible_cleared_new = false;
bool checked_lockers;
bool locker_remains;
TransactionId xmax_new_tuple,
xmax_old_tuple;
uint16 infomask_old_tuple,
infomask2_old_tuple,
infomask_new_tuple,
infomask2_new_tuple;
Assert(ItemPointerIsValid(otid));
gp_expand_protect_catalog_changes(relation);
/*
* Forbid this during a parallel operation, lest it allocate a combocid.
* Other workers might need that combocid for visibility checks, and we
* have no provision for broadcasting it to them.
*/
if (IsInParallelMode())
ereport(ERROR,
(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
errmsg("cannot update tuples during a parallel operation")));
/*
* Fetch the list of attributes to be checked for various operations.
*
* For HOT considerations, this is wasted effort if we fail to update or
* have to put the new tuple on a different page. But we must compute the
* list before obtaining buffer lock --- in the worst case, if we are
* doing an update on one of the relevant system catalogs, we could
* deadlock if we try to fetch the list later. In any case, the relcache
* caches the data so this is usually pretty cheap.
*
* We also need columns used by the replica identity and columns that are
* considered the "key" of rows in the table.
*
* Note that we get copies of each bitmap, so we need not worry about
* relcache flush happening midway through.
*/
hot_attrs = RelationGetIndexAttrBitmap(relation, INDEX_ATTR_BITMAP_ALL);
key_attrs = RelationGetIndexAttrBitmap(relation, INDEX_ATTR_BITMAP_KEY);
id_attrs = RelationGetIndexAttrBitmap(relation,
INDEX_ATTR_BITMAP_IDENTITY_KEY);
block = ItemPointerGetBlockNumber(otid);
buffer = ReadBuffer(relation, block);
page = BufferGetPage(buffer);
interesting_attrs = NULL;
/*
* If the page is already full, there is hardly any chance of doing a HOT
* update on this page. It might be wasteful effort to look for index
* column updates only to later reject HOT updates for lack of space in
* the same page. So we be conservative and only fetch hot_attrs if the
* page is not already full. Since we are already holding a pin on the
* buffer, there is no chance that the buffer can get cleaned up
* concurrently and even if that was possible, in the worst case we lose a
* chance to do a HOT update.
*/
if (!PageIsFull(page))
{
interesting_attrs = bms_add_members(interesting_attrs, hot_attrs);
hot_attrs_checked = true;
}
interesting_attrs = bms_add_members(interesting_attrs, key_attrs);
interesting_attrs = bms_add_members(interesting_attrs, id_attrs);
/*
* Before locking the buffer, pin the visibility map page if it appears to
* be necessary. Since we haven't got the lock yet, someone else might be
* in the middle of changing this, so we'll need to recheck after we have
* the lock.
*/
if (PageIsAllVisible(page))
visibilitymap_pin(relation, block, &vmbuffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(otid));
Assert(ItemIdIsNormal(lp));
/*
* Fill in enough data in oldtup for HeapDetermineModifiedColumns to work
* properly.
*/
oldtup.t_tableOid = RelationGetRelid(relation);
oldtup.t_data = (HeapTupleHeader) PageGetItem(page, lp);
oldtup.t_len = ItemIdGetLength(lp);
oldtup.t_self = *otid;
/* the new tuple is ready, except for this: */
newtup->t_tableOid = RelationGetRelid(relation);
/* Determine columns modified by the update. */
modified_attrs = HeapDetermineModifiedColumns(relation, interesting_attrs,
&oldtup, newtup);
/*
* If we're not updating any "key" column, we can grab a weaker lock type.
* This allows for more concurrency when we are running simultaneously
* with foreign key checks.
*
* Note that if a column gets detoasted while executing the update, but
* the value ends up being the same, this test will fail and we will use
* the stronger lock. This is acceptable; the important case to optimize
* is updates that don't manipulate key columns, not those that
* serendipitiously arrive at the same key values.
*/
if (!bms_overlap(modified_attrs, key_attrs))
{
*lockmode = LockTupleNoKeyExclusive;
mxact_status = MultiXactStatusNoKeyUpdate;
key_intact = true;
/*
* If this is the first possibly-multixact-able operation in the
* current transaction, set my per-backend OldestMemberMXactId
* setting. We can be certain that the transaction will never become a
* member of any older MultiXactIds than that. (We have to do this
* even if we end up just using our own TransactionId below, since
* some other backend could incorporate our XID into a MultiXact
* immediately afterwards.)
*/
MultiXactIdSetOldestMember();
}
else
{
*lockmode = LockTupleExclusive;
mxact_status = MultiXactStatusUpdate;
key_intact = false;
}
/*
* Note: beyond this point, use oldtup not otid to refer to old tuple.
* otid may very well point at newtup->t_self, which we will overwrite
* with the new tuple's location, so there's great risk of confusion if we
* use otid anymore.
*/
l2:
checked_lockers = false;
locker_remains = false;
result = HeapTupleSatisfiesUpdate(relation, &oldtup, cid, buffer);
/* see below about the "no wait" case */
Assert(result != TM_BeingModified || wait);
if (result == TM_Invisible)
{
UnlockReleaseBuffer(buffer);
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("attempted to update invisible tuple")));
}
else if (result == TM_BeingModified && wait)
{
TransactionId xwait;
uint16 infomask;
bool can_continue = false;
/*
* XXX note that we don't consider the "no wait" case here. This
* isn't a problem currently because no caller uses that case, but it
* should be fixed if such a caller is introduced. It wasn't a
* problem previously because this code would always wait, but now
* that some tuple locks do not conflict with one of the lock modes we
* use, it is possible that this case is interesting to handle
* specially.
*
* This may cause failures with third-party code that calls
* heap_update directly.
*/
/* must copy state data before unlocking buffer */
xwait = HeapTupleHeaderGetRawXmax(oldtup.t_data);
infomask = oldtup.t_data->t_infomask;
/*
* Now we have to do something about the existing locker. If it's a
* multi, sleep on it; we might be awakened before it is completely
* gone (or even not sleep at all in some cases); we need to preserve
* it as locker, unless it is gone completely.
*
* If it's not a multi, we need to check for sleeping conditions
* before actually going to sleep. If the update doesn't conflict
* with the locks, we just continue without sleeping (but making sure
* it is preserved).
*
* Before sleeping, we need to acquire tuple lock to establish our
* priority for the tuple (see heap_lock_tuple). LockTuple will
* release us when we are next-in-line for the tuple. Note we must
* not acquire the tuple lock until we're sure we're going to sleep;
* otherwise we're open for race conditions with other transactions
* holding the tuple lock which sleep on us.
*
* If we are forced to "start over" below, we keep the tuple lock;
* this arranges that we stay at the head of the line while rechecking
* tuple state.
*/
if (infomask & HEAP_XMAX_IS_MULTI)
{
TransactionId update_xact;
int remain;
bool current_is_member = false;
if (DoesMultiXactIdConflict((MultiXactId) xwait, infomask,
*lockmode, ¤t_is_member))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/*
* Acquire the lock, if necessary (but skip it when we're
* requesting a lock and already have one; avoids deadlock).
*/
if (!current_is_member)
heap_acquire_tuplock(relation, &(oldtup.t_self), *lockmode,
LockWaitBlock, &have_tuple_lock);
/* wait for multixact */
MultiXactIdWait((MultiXactId) xwait, mxact_status, infomask,
relation, &oldtup.t_self, XLTW_Update,
&remain);
checked_lockers = true;
locker_remains = remain != 0;
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* If xwait had just locked the tuple then some other xact
* could update this tuple before we get to this point. Check
* for xmax change, and start over if so.
*/
if (xmax_infomask_changed(oldtup.t_data->t_infomask,
infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(oldtup.t_data),
xwait))
goto l2;
}
/*
* Note that the multixact may not be done by now. It could have
* surviving members; our own xact or other subxacts of this
* backend, and also any other concurrent transaction that locked
* the tuple with KeyShare if we only got TupleLockUpdate. If
* this is the case, we have to be careful to mark the updated
* tuple with the surviving members in Xmax.
*
* Note that there could have been another update in the
* MultiXact. In that case, we need to check whether it committed
* or aborted. If it aborted we are safe to update it again;
* otherwise there is an update conflict, and we have to return
* TableTuple{Deleted, Updated} below.
*
* In the LockTupleExclusive case, we still need to preserve the
* surviving members: those would include the tuple locks we had
* before this one, which are important to keep in case this
* subxact aborts.
*/
if (!HEAP_XMAX_IS_LOCKED_ONLY(oldtup.t_data->t_infomask))
update_xact = HeapTupleGetUpdateXid(oldtup.t_data);
else
update_xact = InvalidTransactionId;
/*
* There was no UPDATE in the MultiXact; or it aborted. No
* TransactionIdIsInProgress() call needed here, since we called
* MultiXactIdWait() above.
*/
if (!TransactionIdIsValid(update_xact) ||
TransactionIdDidAbort(update_xact))
can_continue = true;
}
else if (TransactionIdIsCurrentTransactionId(xwait))
{
/*
* The only locker is ourselves; we can avoid grabbing the tuple
* lock here, but must preserve our locking information.
*/
checked_lockers = true;
locker_remains = true;
can_continue = true;
}
else if (HEAP_XMAX_IS_KEYSHR_LOCKED(infomask) && key_intact)
{
/*
* If it's just a key-share locker, and we're not changing the key
* columns, we don't need to wait for it to end; but we need to
* preserve it as locker.
*/
checked_lockers = true;
locker_remains = true;
can_continue = true;
}
else
{
/*
* Wait for regular transaction to end; but first, acquire tuple
* lock.
*/
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
heap_acquire_tuplock(relation, &(oldtup.t_self), *lockmode,
LockWaitBlock, &have_tuple_lock);
XactLockTableWait(xwait, relation, &oldtup.t_self,
XLTW_Update);
checked_lockers = true;
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* xwait is done, but if xwait had just locked the tuple then some
* other xact could update this tuple before we get to this point.
* Check for xmax change, and start over if so.
*/
if (xmax_infomask_changed(oldtup.t_data->t_infomask, infomask) ||
!TransactionIdEquals(xwait,
HeapTupleHeaderGetRawXmax(oldtup.t_data)))
goto l2;
/* Otherwise check if it committed or aborted */
UpdateXmaxHintBits(oldtup.t_data, buffer, xwait, relation);
if (oldtup.t_data->t_infomask & HEAP_XMAX_INVALID)
can_continue = true;
}
if (can_continue)
result = TM_Ok;
else if (!ItemPointerEquals(&oldtup.t_self, &oldtup.t_data->t_ctid) ||
HeapTupleHeaderIndicatesMovedPartitions(oldtup.t_data))
result = TM_Updated;
else
result = TM_Deleted;
}
if (crosscheck != InvalidSnapshot && result == TM_Ok)
{
/* Perform additional check for transaction-snapshot mode RI updates */
if (!HeapTupleSatisfiesVisibility(relation, &oldtup, crosscheck, buffer))
{
result = TM_Updated;
Assert(!ItemPointerEquals(&oldtup.t_self, &oldtup.t_data->t_ctid));
}
}
if (result != TM_Ok)
{
Assert(result == TM_SelfModified ||
result == TM_Updated ||
result == TM_Deleted ||
result == TM_BeingModified);
Assert(!(oldtup.t_data->t_infomask & HEAP_XMAX_INVALID));
Assert(result != TM_Updated ||
!ItemPointerEquals(&oldtup.t_self, &oldtup.t_data->t_ctid));
tmfd->ctid = oldtup.t_data->t_ctid;
tmfd->xmax = HeapTupleHeaderGetUpdateXid(oldtup.t_data);
if (result == TM_SelfModified)
tmfd->cmax = HeapTupleHeaderGetCmax(oldtup.t_data);
else
tmfd->cmax = InvalidCommandId;
UnlockReleaseBuffer(buffer);
if (have_tuple_lock)
UnlockTupleTuplock(relation, &(oldtup.t_self), *lockmode);
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
bms_free(hot_attrs);
bms_free(key_attrs);
bms_free(id_attrs);
bms_free(modified_attrs);
bms_free(interesting_attrs);
return result;
}
/*
* If we didn't pin the visibility map page and the page has become all
* visible while we were busy locking the buffer, or during some
* subsequent window during which we had it unlocked, we'll have to unlock
* and re-lock, to avoid holding the buffer lock across an I/O. That's a
* bit unfortunate, especially since we'll now have to recheck whether the
* tuple has been locked or updated under us, but hopefully it won't
* happen very often.
*/
if (vmbuffer == InvalidBuffer && PageIsAllVisible(page))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
visibilitymap_pin(relation, block, &vmbuffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
goto l2;
}
/* Fill in transaction status data */
/*
* If the tuple we're updating is locked, we need to preserve the locking
* info in the old tuple's Xmax. Prepare a new Xmax value for this.
*/
compute_new_xmax_infomask(HeapTupleHeaderGetRawXmax(oldtup.t_data),
oldtup.t_data->t_infomask,
oldtup.t_data->t_infomask2,
xid, *lockmode, true,
&xmax_old_tuple, &infomask_old_tuple,
&infomask2_old_tuple);
/*
* And also prepare an Xmax value for the new copy of the tuple. If there
* was no xmax previously, or there was one but all lockers are now gone,
* then use InvalidXid; otherwise, get the xmax from the old tuple. (In
* rare cases that might also be InvalidXid and yet not have the
* HEAP_XMAX_INVALID bit set; that's fine.)
*/
if ((oldtup.t_data->t_infomask & HEAP_XMAX_INVALID) ||
HEAP_LOCKED_UPGRADED(oldtup.t_data->t_infomask) ||
(checked_lockers && !locker_remains))
xmax_new_tuple = InvalidTransactionId;
else
xmax_new_tuple = HeapTupleHeaderGetRawXmax(oldtup.t_data);
if (!TransactionIdIsValid(xmax_new_tuple))
{
infomask_new_tuple = HEAP_XMAX_INVALID;
infomask2_new_tuple = 0;
}
else
{
/*
* If we found a valid Xmax for the new tuple, then the infomask bits
* to use on the new tuple depend on what was there on the old one.
* Note that since we're doing an update, the only possibility is that
* the lockers had FOR KEY SHARE lock.
*/
if (oldtup.t_data->t_infomask & HEAP_XMAX_IS_MULTI)
{
GetMultiXactIdHintBits(xmax_new_tuple, &infomask_new_tuple,
&infomask2_new_tuple);
}
else
{
infomask_new_tuple = HEAP_XMAX_KEYSHR_LOCK | HEAP_XMAX_LOCK_ONLY;
infomask2_new_tuple = 0;
}
}
/*
* Prepare the new tuple with the appropriate initial values of Xmin and
* Xmax, as well as initial infomask bits as computed above.
*/
newtup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
newtup->t_data->t_infomask2 &= ~(HEAP2_XACT_MASK);
HeapTupleHeaderSetXmin(newtup->t_data, xid);
HeapTupleHeaderSetCmin(newtup->t_data, cid);
newtup->t_data->t_infomask |= HEAP_UPDATED | infomask_new_tuple;
newtup->t_data->t_infomask2 |= infomask2_new_tuple;
HeapTupleHeaderSetXmax(newtup->t_data, xmax_new_tuple);
/*
* Replace cid with a combo cid if necessary. Note that we already put
* the plain cid into the new tuple.
*/
HeapTupleHeaderAdjustCmax(oldtup.t_data, &cid, &iscombo);
/*
* If the toaster needs to be activated, OR if the new tuple will not fit
* on the same page as the old, then we need to release the content lock
* (but not the pin!) on the old tuple's buffer while we are off doing
* TOAST and/or table-file-extension work. We must mark the old tuple to
* show that it's locked, else other processes may try to update it
* themselves.
*
* We need to invoke the toaster if there are already any out-of-line
* toasted values present, or if the new tuple is over-threshold.
*/
if (relation->rd_rel->relkind != RELKIND_RELATION &&
relation->rd_rel->relkind != RELKIND_MATVIEW)
{
/* toast table entries should never be recursively toasted */
Assert(!HeapTupleHasExternal(&oldtup));
Assert(!HeapTupleHasExternal(newtup));
need_toast = false;
}
else
need_toast = (HeapTupleHasExternal(&oldtup) ||
HeapTupleHasExternal(newtup) ||
newtup->t_len > TOAST_TUPLE_THRESHOLD);
pagefree = PageGetHeapFreeSpace(page);
newtupsize = MAXALIGN(newtup->t_len);
if (need_toast || newtupsize > pagefree)
{
TransactionId xmax_lock_old_tuple;
uint16 infomask_lock_old_tuple,
infomask2_lock_old_tuple;
bool cleared_all_frozen = false;
/*
* To prevent concurrent sessions from updating the tuple, we have to
* temporarily mark it locked, while we release the page-level lock.
*
* To satisfy the rule that any xid potentially appearing in a buffer
* written out to disk, we unfortunately have to WAL log this
* temporary modification. We can reuse xl_heap_lock for this
* purpose. If we crash/error before following through with the
* actual update, xmax will be of an aborted transaction, allowing
* other sessions to proceed.
*/
/*
* Compute xmax / infomask appropriate for locking the tuple. This has
* to be done separately from the combo that's going to be used for
* updating, because the potentially created multixact would otherwise
* be wrong.
*/
compute_new_xmax_infomask(HeapTupleHeaderGetRawXmax(oldtup.t_data),
oldtup.t_data->t_infomask,
oldtup.t_data->t_infomask2,
xid, *lockmode, false,
&xmax_lock_old_tuple, &infomask_lock_old_tuple,
&infomask2_lock_old_tuple);
Assert(HEAP_XMAX_IS_LOCKED_ONLY(infomask_lock_old_tuple));
START_CRIT_SECTION();
/* Clear obsolete visibility flags ... */
oldtup.t_data->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
oldtup.t_data->t_infomask2 &= ~HEAP_KEYS_UPDATED;
HeapTupleClearHotUpdated(&oldtup);
/* ... and store info about transaction updating this tuple */
Assert(TransactionIdIsValid(xmax_lock_old_tuple));
HeapTupleHeaderSetXmax(oldtup.t_data, xmax_lock_old_tuple);
oldtup.t_data->t_infomask |= infomask_lock_old_tuple;
oldtup.t_data->t_infomask2 |= infomask2_lock_old_tuple;
HeapTupleHeaderSetCmax(oldtup.t_data, cid, iscombo);
/* temporarily make it look not-updated, but locked */
oldtup.t_data->t_ctid = oldtup.t_self;
/*
* Clear all-frozen bit on visibility map if needed. We could
* immediately reset ALL_VISIBLE, but given that the WAL logging
* overhead would be unchanged, that doesn't seem necessarily
* worthwhile.
*/
if (PageIsAllVisible(BufferGetPage(buffer)) &&
visibilitymap_clear(relation, block, vmbuffer,
VISIBILITYMAP_ALL_FROZEN))
cleared_all_frozen = true;
MarkBufferDirty(buffer);
if (RelationNeedsWAL(relation))
{
xl_heap_lock xlrec;
XLogRecPtr recptr;
XLogBeginInsert();
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
xlrec.offnum = ItemPointerGetOffsetNumber(&oldtup.t_self);
xlrec.locking_xid = xmax_lock_old_tuple;
xlrec.infobits_set = compute_infobits(oldtup.t_data->t_infomask,
oldtup.t_data->t_infomask2);
xlrec.flags =
cleared_all_frozen ? XLH_LOCK_ALL_FROZEN_CLEARED : 0;
XLogRegisterData((char *) &xlrec, SizeOfHeapLock);
recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_LOCK);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/*
* Let the toaster do its thing, if needed.
*
* Note: below this point, heaptup is the data we actually intend to
* store into the relation; newtup is the caller's original untoasted
* data.
*/
if (need_toast)
{
/* Note we always use WAL and FSM during updates */
heaptup = toast_insert_or_update(relation, newtup, &oldtup,
TOAST_TUPLE_TARGET, false, 0);
newtupsize = MAXALIGN(heaptup->t_len);
}
else
heaptup = newtup;
/*
* Now, do we need a new page for the tuple, or not? This is a bit
* tricky since someone else could have added tuples to the page while
* we weren't looking. We have to recheck the available space after
* reacquiring the buffer lock. But don't bother to do that if the
* former amount of free space is still not enough; it's unlikely
* there's more free now than before.
*
* What's more, if we need to get a new page, we will need to acquire
* buffer locks on both old and new pages. To avoid deadlock against
* some other backend trying to get the same two locks in the other
* order, we must be consistent about the order we get the locks in.
* We use the rule "lock the lower-numbered page of the relation
* first". To implement this, we must do RelationGetBufferForTuple
* while not holding the lock on the old page, and we must rely on it
* to get the locks on both pages in the correct order.
*/
if (newtupsize > pagefree)
{
/* Assume there's no chance to put heaptup on same page. */
newbuf = RelationGetBufferForTuple(relation, heaptup->t_len,
buffer, 0, NULL,
&vmbuffer_new, &vmbuffer);
}
else
{
/* Re-acquire the lock on the old tuple's page. */
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
/* Re-check using the up-to-date free space */
pagefree = PageGetHeapFreeSpace(page);
if (newtupsize > pagefree)
{
/*
* Rats, it doesn't fit anymore. We must now unlock and
* relock to avoid deadlock. Fortunately, this path should
* seldom be taken.
*/
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
newbuf = RelationGetBufferForTuple(relation, heaptup->t_len,
buffer, 0, NULL,
&vmbuffer_new, &vmbuffer);
}
else
{
/* OK, it fits here, so we're done. */
newbuf = buffer;
}
}
}
else
{
/* No TOAST work needed, and it'll fit on same page */
newbuf = buffer;
heaptup = newtup;
}
/*
* We're about to do the actual update -- check for conflict first, to
* avoid possibly having to roll back work we've just done.
*
* This is safe without a recheck as long as there is no possibility of
* another process scanning the pages between this check and the update
* being visible to the scan (i.e., exclusive buffer content lock(s) are
* continuously held from this point until the tuple update is visible).
*
* For the new tuple the only check needed is at the relation level, but
* since both tuples are in the same relation and the check for oldtup
* will include checking the relation level, there is no benefit to a
* separate check for the new tuple.
*/
CheckForSerializableConflictIn(relation, &oldtup, buffer);
/*
* At this point newbuf and buffer are both pinned and locked, and newbuf
* has enough space for the new tuple. If they are the same buffer, only
* one pin is held.
*/
if (newbuf == buffer)
{
/*
* Since the new tuple is going into the same page, we might be able
* to do a HOT update. Check if any of the index columns have been
* changed. If the page was already full, we may have skipped checking
* for index columns, and also can't do a HOT update.
*/
if (hot_attrs_checked && !bms_overlap(modified_attrs, hot_attrs))
use_hot_update = true;
}
else
{
/* Set a hint that the old page could use prune/defrag */
PageSetFull(page);
}
/*
* Compute replica identity tuple before entering the critical section so
* we don't PANIC upon a memory allocation failure.
* ExtractReplicaIdentity() will return NULL if nothing needs to be
* logged.
*/
old_key_tuple = ExtractReplicaIdentity(relation, &oldtup,
bms_overlap(modified_attrs, id_attrs),
&old_key_copied);
/* NO EREPORT(ERROR) from here till changes are logged */
START_CRIT_SECTION();
/*
* If this transaction commits, the old tuple will become DEAD sooner or
* later. Set flag that this page is a candidate for pruning once our xid
* falls below the OldestXmin horizon. If the transaction finally aborts,
* the subsequent page pruning will be a no-op and the hint will be
* cleared.
*
* XXX Should we set hint on newbuf as well? If the transaction aborts,
* there would be a prunable tuple in the newbuf; but for now we choose
* not to optimize for aborts. Note that heap_xlog_update must be kept in
* sync if this decision changes.
*/
PageSetPrunable(page, xid);
if (use_hot_update)
{
/* Mark the old tuple as HOT-updated */
HeapTupleSetHotUpdated(&oldtup);
/* And mark the new tuple as heap-only */
HeapTupleSetHeapOnly(heaptup);
/* Mark the caller's copy too, in case different from heaptup */
HeapTupleSetHeapOnly(newtup);
}
else
{
/* Make sure tuples are correctly marked as not-HOT */
HeapTupleClearHotUpdated(&oldtup);
HeapTupleClearHeapOnly(heaptup);
HeapTupleClearHeapOnly(newtup);
}
RelationPutHeapTuple(relation, newbuf, heaptup, false); /* insert new tuple */
/* Clear obsolete visibility flags, possibly set by ourselves above... */
oldtup.t_data->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
oldtup.t_data->t_infomask2 &= ~HEAP_KEYS_UPDATED;
/* ... and store info about transaction updating this tuple */
Assert(TransactionIdIsValid(xmax_old_tuple));
HeapTupleHeaderSetXmax(oldtup.t_data, xmax_old_tuple);
oldtup.t_data->t_infomask |= infomask_old_tuple;
oldtup.t_data->t_infomask2 |= infomask2_old_tuple;
HeapTupleHeaderSetCmax(oldtup.t_data, cid, iscombo);
/* record address of new tuple in t_ctid of old one */
oldtup.t_data->t_ctid = heaptup->t_self;
/* clear PD_ALL_VISIBLE flags, reset all visibilitymap bits */
if (PageIsAllVisible(BufferGetPage(buffer)))
{
all_visible_cleared = true;
PageClearAllVisible(BufferGetPage(buffer));
visibilitymap_clear(relation, BufferGetBlockNumber(buffer),
vmbuffer, VISIBILITYMAP_VALID_BITS);
}
if (newbuf != buffer && PageIsAllVisible(BufferGetPage(newbuf)))
{
all_visible_cleared_new = true;
PageClearAllVisible(BufferGetPage(newbuf));
visibilitymap_clear(relation, BufferGetBlockNumber(newbuf),
vmbuffer_new, VISIBILITYMAP_VALID_BITS);
}
if (newbuf != buffer)
MarkBufferDirty(newbuf);
MarkBufferDirty(buffer);
/* XLOG stuff */
if (RelationNeedsWAL(relation))
{
XLogRecPtr recptr;
/*
* For logical decoding we need combocids to properly decode the
* catalog.
*/
if (RelationIsAccessibleInLogicalDecoding(relation))
{
log_heap_new_cid(relation, &oldtup);
log_heap_new_cid(relation, heaptup);
}
recptr = log_heap_update(relation, buffer,
newbuf, &oldtup, heaptup,
old_key_tuple,
all_visible_cleared,
all_visible_cleared_new);
if (newbuf != buffer)
{
PageSetLSN(BufferGetPage(newbuf), recptr);
}
PageSetLSN(BufferGetPage(buffer), recptr);
}
END_CRIT_SECTION();
if (newbuf != buffer)
LockBuffer(newbuf, BUFFER_LOCK_UNLOCK);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
/*
* Mark old tuple for invalidation from system caches at next command
* boundary, and mark the new tuple for invalidation in case we abort. We
* have to do this before releasing the buffer because oldtup is in the
* buffer. (heaptup is all in local memory, but it's necessary to process
* both tuple versions in one call to inval.c so we can avoid redundant
* sinval messages.)
*/
CacheInvalidateHeapTuple(relation, &oldtup, heaptup);
/* Now we can release the buffer(s) */
if (newbuf != buffer)
ReleaseBuffer(newbuf);
ReleaseBuffer(buffer);
if (BufferIsValid(vmbuffer_new))
ReleaseBuffer(vmbuffer_new);
if (BufferIsValid(vmbuffer))
ReleaseBuffer(vmbuffer);
/*
* Release the lmgr tuple lock, if we had it.
*/
if (have_tuple_lock)
UnlockTupleTuplock(relation, &(oldtup.t_self), *lockmode);
pgstat_count_heap_update(relation, false);
/*
* If heaptup is a private copy, release it. Don't forget to copy t_self
* back to the caller's image, too.
*/
if (heaptup != newtup)
{
newtup->t_self = heaptup->t_self;
heap_freetuple(heaptup);
}
if (old_key_tuple != NULL && old_key_copied)
heap_freetuple(old_key_tuple);
bms_free(hot_attrs);
bms_free(key_attrs);
bms_free(id_attrs);
bms_free(modified_attrs);
bms_free(interesting_attrs);
return TM_Ok;
}
TM_Result
heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
CommandId cid, Snapshot crosscheck, bool wait,
TM_FailureData *tmfd, LockTupleMode *lockmode)
{
return heap_update_internal(relation, otid, newtup,
cid, crosscheck, wait,
tmfd, lockmode,
/* simple */ false);
}
/*
* Check if the specified attribute's value is same in both given tuples.
* Subroutine for HeapDetermineModifiedColumns.
*/
static bool
heap_tuple_attr_equals(TupleDesc tupdesc, int attrnum,
HeapTuple tup1, HeapTuple tup2)
{
Datum value1,
value2;
bool isnull1,
isnull2;
Form_pg_attribute att;
/*
* If it's a whole-tuple reference, say "not equal". It's not really
* worth supporting this case, since it could only succeed after a no-op
* update, which is hardly a case worth optimizing for.
*/
if (attrnum == 0)
return false;
/*
* Likewise, automatically say "not equal" for any system attribute other
* than tableOID; we cannot expect these to be consistent in a HOT chain,
* or even to be set correctly yet in the new tuple.
*/
if (attrnum < 0)
{
if (attrnum != TableOidAttributeNumber)
return false;
}
/*
* Extract the corresponding values. XXX this is pretty inefficient if
* there are many indexed columns. Should HeapDetermineModifiedColumns do
* a single heap_deform_tuple call on each tuple, instead? But that
* doesn't work for system columns ...
*/
value1 = heap_getattr(tup1, attrnum, tupdesc, &isnull1);
value2 = heap_getattr(tup2, attrnum, tupdesc, &isnull2);
/*
* If one value is NULL and other is not, then they are certainly not
* equal
*/
if (isnull1 != isnull2)
return false;
/*
* If both are NULL, they can be considered equal.
*/
if (isnull1)
return true;
/*
* We do simple binary comparison of the two datums. This may be overly
* strict because there can be multiple binary representations for the
* same logical value. But we should be OK as long as there are no false
* positives. Using a type-specific equality operator is messy because
* there could be multiple notions of equality in different operator
* classes; furthermore, we cannot safely invoke user-defined functions
* while holding exclusive buffer lock.
*/
if (attrnum <= 0)
{
/* The only allowed system columns are OIDs, so do this */
return (DatumGetObjectId(value1) == DatumGetObjectId(value2));
}
else
{
Assert(attrnum <= tupdesc->natts);
att = TupleDescAttr(tupdesc, attrnum - 1);
return datumIsEqual(value1, value2, att->attbyval, att->attlen);
}
}
/*
* Check which columns are being updated.
*
* Given an updated tuple, determine (and return into the output bitmapset),
* from those listed as interesting, the set of columns that changed.
*
* The input bitmapset is destructively modified; that is OK since this is
* invoked at most once in heap_update.
*/
static Bitmapset *
HeapDetermineModifiedColumns(Relation relation, Bitmapset *interesting_cols,
HeapTuple oldtup, HeapTuple newtup)
{
int attnum;
Bitmapset *modified = NULL;
while ((attnum = bms_first_member(interesting_cols)) >= 0)
{
attnum += FirstLowInvalidHeapAttributeNumber;
if (!heap_tuple_attr_equals(RelationGetDescr(relation),
attnum, oldtup, newtup))
modified = bms_add_member(modified,
attnum - FirstLowInvalidHeapAttributeNumber);
}
return modified;
}
/*
* simple_heap_update - replace a tuple
*
* This routine may be used to update a tuple when concurrent updates of
* the target tuple are not expected (for example, because we have a lock
* on the relation associated with the tuple). Any failure is reported
* via ereport().
*/
void
simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup)
{
TM_Result result;
TM_FailureData tmfd;
LockTupleMode lockmode;
result = heap_update_internal(relation, otid, tup,
GetCurrentCommandId(true), InvalidSnapshot,
true /* wait for commit */ ,
&tmfd, &lockmode,
/* simple */ true);
switch (result)
{
case TM_SelfModified:
/* Tuple was already updated in current command? */
elog(ERROR, "tuple already updated by self");
break;
case TM_Ok:
/* done successfully */
break;
case TM_Updated:
elog(ERROR, "tuple concurrently updated");
break;
case TM_Deleted:
elog(ERROR, "tuple concurrently deleted");
break;
default:
elog(ERROR, "unrecognized heap_update status: %u", result);
break;
}
}
/*
* Return the MultiXactStatus corresponding to the given tuple lock mode.
*/
static MultiXactStatus
get_mxact_status_for_lock(LockTupleMode mode, bool is_update)
{
int retval;
if (is_update)
retval = tupleLockExtraInfo[mode].updstatus;
else
retval = tupleLockExtraInfo[mode].lockstatus;
if (retval == -1)
elog(ERROR, "invalid lock tuple mode %d/%s", mode,
is_update ? "true" : "false");
return (MultiXactStatus) retval;
}
/*
* heap_lock_tuple - lock a tuple in shared or exclusive mode
*
* Note that this acquires a buffer pin, which the caller must release.
*
* Input parameters:
* relation: relation containing tuple (caller must hold suitable lock)
* tid: TID of tuple to lock
* cid: current command ID (used for visibility test, and stored into
* tuple's cmax if lock is successful)
* mode: indicates if shared or exclusive tuple lock is desired
* wait_policy: what to do if tuple lock is not available
* follow_updates: if true, follow the update chain to also lock descendant
* tuples.
*
* Output parameters:
* *tuple: all fields filled in
* *buffer: set to buffer holding tuple (pinned but not locked at exit)
* *tmfd: filled in failure cases (see below)
*
* Function results are the same as the ones for table_tuple_lock().
*
* In the failure cases other than TM_Invisible, the routine fills
* *tmfd with the tuple's t_ctid, t_xmax (resolving a possible MultiXact,
* if necessary), and t_cmax (the last only for TM_SelfModified,
* since we cannot obtain cmax from a combocid generated by another
* transaction).
* See comments for struct TM_FailureData for additional info.
*
* See README.tuplock for a thorough explanation of this mechanism.
*/
TM_Result
heap_lock_tuple(Relation relation, HeapTuple tuple,
CommandId cid, LockTupleMode mode, LockWaitPolicy wait_policy,
bool follow_updates,
Buffer *buffer, TM_FailureData *tmfd)
{
TM_Result result;
ItemPointer tid = &(tuple->t_self);
ItemId lp;
Page page;
Buffer vmbuffer = InvalidBuffer;
BlockNumber block;
TransactionId xid,
xmax;
uint16 old_infomask,
new_infomask,
new_infomask2;
bool first_time = true;
bool skip_tuple_lock = false;
bool have_tuple_lock = false;
bool cleared_all_frozen = false;
*buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
block = ItemPointerGetBlockNumber(tid);
/*
* Before locking the buffer, pin the visibility map page if it appears to
* be necessary. Since we haven't got the lock yet, someone else might be
* in the middle of changing this, so we'll need to recheck after we have
* the lock.
*/
if (PageIsAllVisible(BufferGetPage(*buffer)))
visibilitymap_pin(relation, block, &vmbuffer);
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
page = BufferGetPage(*buffer);
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid));
Assert(ItemIdIsNormal(lp));
tuple->t_data = (HeapTupleHeader) PageGetItem(page, lp);
tuple->t_len = ItemIdGetLength(lp);
tuple->t_tableOid = RelationGetRelid(relation);
l3:
result = HeapTupleSatisfiesUpdate(relation, tuple, cid, *buffer);
if (result == TM_Invisible)
{
/*
* This is possible, but only when locking a tuple for ON CONFLICT
* UPDATE. We return this value here rather than throwing an error in
* order to give that case the opportunity to throw a more specific
* error.
*/
result = TM_Invisible;
goto out_locked;
}
else if (result == TM_BeingModified ||
result == TM_Updated ||
result == TM_Deleted)
{
TransactionId xwait;
uint16 infomask;
uint16 infomask2;
bool require_sleep;
ItemPointerData t_ctid;
/* must copy state data before unlocking buffer */
xwait = HeapTupleHeaderGetRawXmax(tuple->t_data);
infomask = tuple->t_data->t_infomask;
infomask2 = tuple->t_data->t_infomask2;
ItemPointerCopy(&tuple->t_data->t_ctid, &t_ctid);
LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
/*
* If any subtransaction of the current top transaction already holds
* a lock as strong as or stronger than what we're requesting, we
* effectively hold the desired lock already. We *must* succeed
* without trying to take the tuple lock, else we will deadlock
* against anyone wanting to acquire a stronger lock.
*
* Note we only do this the first time we loop on the HTSU result;
* there is no point in testing in subsequent passes, because
* evidently our own transaction cannot have acquired a new lock after
* the first time we checked.
*/
if (first_time)
{
first_time = false;
if (infomask & HEAP_XMAX_IS_MULTI)
{
int i;
int nmembers;
MultiXactMember *members;
/*
* We don't need to allow old multixacts here; if that had
* been the case, HeapTupleSatisfiesUpdate would have returned
* MayBeUpdated and we wouldn't be here.
*/
nmembers =
GetMultiXactIdMembers(xwait, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(infomask));
for (i = 0; i < nmembers; i++)
{
/* only consider members of our own transaction */
if (!TransactionIdIsCurrentTransactionId(members[i].xid))
continue;
if (TUPLOCK_from_mxstatus(members[i].status) >= mode)
{
pfree(members);
result = TM_Ok;
goto out_unlocked;
}
else
{
/*
* Disable acquisition of the heavyweight tuple lock.
* Otherwise, when promoting a weaker lock, we might
* deadlock with another locker that has acquired the
* heavyweight tuple lock and is waiting for our
* transaction to finish.
*
* Note that in this case we still need to wait for
* the multixact if required, to avoid acquiring
* conflicting locks.
*/
skip_tuple_lock = true;
}
}
if (members)
pfree(members);
}
else if (TransactionIdIsCurrentTransactionId(xwait))
{
switch (mode)
{
case LockTupleKeyShare:
Assert(HEAP_XMAX_IS_KEYSHR_LOCKED(infomask) ||
HEAP_XMAX_IS_SHR_LOCKED(infomask) ||
HEAP_XMAX_IS_EXCL_LOCKED(infomask));
result = TM_Ok;
goto out_unlocked;
case LockTupleShare:
if (HEAP_XMAX_IS_SHR_LOCKED(infomask) ||
HEAP_XMAX_IS_EXCL_LOCKED(infomask))
{
result = TM_Ok;
goto out_unlocked;
}
break;
case LockTupleNoKeyExclusive:
if (HEAP_XMAX_IS_EXCL_LOCKED(infomask))
{
result = TM_Ok;
goto out_unlocked;
}
break;
case LockTupleExclusive:
if (HEAP_XMAX_IS_EXCL_LOCKED(infomask) &&
infomask2 & HEAP_KEYS_UPDATED)
{
result = TM_Ok;
goto out_unlocked;
}
break;
}
}
}
/*
* Initially assume that we will have to wait for the locking
* transaction(s) to finish. We check various cases below in which
* this can be turned off.
*/
require_sleep = true;
if (mode == LockTupleKeyShare)
{
/*
* If we're requesting KeyShare, and there's no update present, we
* don't need to wait. Even if there is an update, we can still
* continue if the key hasn't been modified.
*
* However, if there are updates, we need to walk the update chain
* to mark future versions of the row as locked, too. That way,
* if somebody deletes that future version, we're protected
* against the key going away. This locking of future versions
* could block momentarily, if a concurrent transaction is
* deleting a key; or it could return a value to the effect that
* the transaction deleting the key has already committed. So we
* do this before re-locking the buffer; otherwise this would be
* prone to deadlocks.
*
* Note that the TID we're locking was grabbed before we unlocked
* the buffer. For it to change while we're not looking, the
* other properties we're testing for below after re-locking the
* buffer would also change, in which case we would restart this
* loop above.
*/
if (!(infomask2 & HEAP_KEYS_UPDATED))
{
bool updated;
updated = !HEAP_XMAX_IS_LOCKED_ONLY(infomask);
/*
* If there are updates, follow the update chain; bail out if
* that cannot be done.
*/
if (follow_updates && updated)
{
TM_Result res;
res = heap_lock_updated_tuple(relation, tuple, &t_ctid,
GetCurrentTransactionId(),
mode);
if (res != TM_Ok)
{
result = res;
/* recovery code expects to have buffer lock held */
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
goto failed;
}
}
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* Make sure it's still an appropriate lock, else start over.
* Also, if it wasn't updated before we released the lock, but
* is updated now, we start over too; the reason is that we
* now need to follow the update chain to lock the new
* versions.
*/
if (!HeapTupleHeaderIsOnlyLocked(tuple->t_data) &&
((tuple->t_data->t_infomask2 & HEAP_KEYS_UPDATED) ||
!updated))
goto l3;
/* Things look okay, so we can skip sleeping */
require_sleep = false;
/*
* Note we allow Xmax to change here; other updaters/lockers
* could have modified it before we grabbed the buffer lock.
* However, this is not a problem, because with the recheck we
* just did we ensure that they still don't conflict with the
* lock we want.
*/
}
}
else if (mode == LockTupleShare)
{
/*
* If we're requesting Share, we can similarly avoid sleeping if
* there's no update and no exclusive lock present.
*/
if (HEAP_XMAX_IS_LOCKED_ONLY(infomask) &&
!HEAP_XMAX_IS_EXCL_LOCKED(infomask))
{
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* Make sure it's still an appropriate lock, else start over.
* See above about allowing xmax to change.
*/
if (!HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_data->t_infomask) ||
HEAP_XMAX_IS_EXCL_LOCKED(tuple->t_data->t_infomask))
goto l3;
require_sleep = false;
}
}
else if (mode == LockTupleNoKeyExclusive)
{
/*
* If we're requesting NoKeyExclusive, we might also be able to
* avoid sleeping; just ensure that there no conflicting lock
* already acquired.
*/
if (infomask & HEAP_XMAX_IS_MULTI)
{
if (!DoesMultiXactIdConflict((MultiXactId) xwait, infomask,
mode, NULL))
{
/*
* No conflict, but if the xmax changed under us in the
* meantime, start over.
*/
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
if (xmax_infomask_changed(tuple->t_data->t_infomask, infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(tuple->t_data),
xwait))
goto l3;
/* otherwise, we're good */
require_sleep = false;
}
}
else if (HEAP_XMAX_IS_KEYSHR_LOCKED(infomask))
{
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
/* if the xmax changed in the meantime, start over */
if (xmax_infomask_changed(tuple->t_data->t_infomask, infomask) ||
!TransactionIdEquals(
HeapTupleHeaderGetRawXmax(tuple->t_data),
xwait))
goto l3;
/* otherwise, we're good */
require_sleep = false;
}
}
/*
* As a check independent from those above, we can also avoid sleeping
* if the current transaction is the sole locker of the tuple. Note
* that the strength of the lock already held is irrelevant; this is
* not about recording the lock in Xmax (which will be done regardless
* of this optimization, below). Also, note that the cases where we
* hold a lock stronger than we are requesting are already handled
* above by not doing anything.
*
* Note we only deal with the non-multixact case here; MultiXactIdWait
* is well equipped to deal with this situation on its own.
*/
if (require_sleep && !(infomask & HEAP_XMAX_IS_MULTI) &&
TransactionIdIsCurrentTransactionId(xwait))
{
/* ... but if the xmax changed in the meantime, start over */
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
if (xmax_infomask_changed(tuple->t_data->t_infomask, infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(tuple->t_data),
xwait))
goto l3;
Assert(HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_data->t_infomask));
require_sleep = false;
}
/*
* Time to sleep on the other transaction/multixact, if necessary.
*
* If the other transaction is an update/delete that's already
* committed, then sleeping cannot possibly do any good: if we're
* required to sleep, get out to raise an error instead.
*
* By here, we either have already acquired the buffer exclusive lock,
* or we must wait for the locking transaction or multixact; so below
* we ensure that we grab buffer lock after the sleep.
*/
if (require_sleep && (result == TM_Updated || result == TM_Deleted))
{
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
goto failed;
}
else if (require_sleep)
{
/*
* Acquire tuple lock to establish our priority for the tuple, or
* die trying. LockTuple will release us when we are next-in-line
* for the tuple. We must do this even if we are share-locking,
* but not if we already have a weaker lock on the tuple.
*
* If we are forced to "start over" below, we keep the tuple lock;
* this arranges that we stay at the head of the line while
* rechecking tuple state.
*/
if (!skip_tuple_lock &&
!heap_acquire_tuplock(relation, tid, mode, wait_policy,
&have_tuple_lock))
{
/*
* This can only happen if wait_policy is Skip and the lock
* couldn't be obtained.
*/
result = TM_WouldBlock;
/* recovery code expects to have buffer lock held */
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
goto failed;
}
if (infomask & HEAP_XMAX_IS_MULTI)
{
MultiXactStatus status = get_mxact_status_for_lock(mode, false);
/* We only ever lock tuples, never update them */
if (status >= MultiXactStatusNoKeyUpdate)
elog(ERROR, "invalid lock mode in heap_lock_tuple");
/* wait for multixact to end, or die trying */
switch (wait_policy)
{
case LockWaitBlock:
MultiXactIdWait((MultiXactId) xwait, status, infomask,
relation, &tuple->t_self, XLTW_Lock, NULL);
break;
case LockWaitSkip:
if (!ConditionalMultiXactIdWait((MultiXactId) xwait,
status, infomask, relation,
NULL))
{
result = TM_WouldBlock;
/* recovery code expects to have buffer lock held */
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
goto failed;
}
break;
case LockWaitError:
if (!ConditionalMultiXactIdWait((MultiXactId) xwait,
status, infomask, relation,
NULL))
ereport(ERROR,
(errcode(ERRCODE_LOCK_NOT_AVAILABLE),
errmsg("could not obtain lock on row in relation \"%s\"",
RelationGetRelationName(relation))));
break;
}
/*
* Of course, the multixact might not be done here: if we're
* requesting a light lock mode, other transactions with light
* locks could still be alive, as well as locks owned by our
* own xact or other subxacts of this backend. We need to
* preserve the surviving MultiXact members. Note that it
* isn't absolutely necessary in the latter case, but doing so
* is simpler.
*/
}
else
{
/* wait for regular transaction to end, or die trying */
switch (wait_policy)
{
case LockWaitBlock:
XactLockTableWait(xwait, relation, &tuple->t_self,
XLTW_Lock);
break;
case LockWaitSkip:
if (!ConditionalXactLockTableWait(xwait))
{
result = TM_WouldBlock;
/* recovery code expects to have buffer lock held */
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
goto failed;
}
break;
case LockWaitError:
if (!ConditionalXactLockTableWait(xwait))
ereport(ERROR,
(errcode(ERRCODE_LOCK_NOT_AVAILABLE),
errmsg("could not obtain lock on row in relation \"%s\"",
RelationGetRelationName(relation))));
break;
}
}
/* if there are updates, follow the update chain */
if (follow_updates && !HEAP_XMAX_IS_LOCKED_ONLY(infomask))
{
TM_Result res;
res = heap_lock_updated_tuple(relation, tuple, &t_ctid,
GetCurrentTransactionId(),
mode);
if (res != TM_Ok)
{
result = res;
/* recovery code expects to have buffer lock held */
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
goto failed;
}
}
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* xwait is done, but if xwait had just locked the tuple then some
* other xact could update this tuple before we get to this point.
* Check for xmax change, and start over if so.
*/
if (xmax_infomask_changed(tuple->t_data->t_infomask, infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(tuple->t_data),
xwait))
goto l3;
if (!(infomask & HEAP_XMAX_IS_MULTI))
{
/*
* Otherwise check if it committed or aborted. Note we cannot
* be here if the tuple was only locked by somebody who didn't
* conflict with us; that would have been handled above. So
* that transaction must necessarily be gone by now. But
* don't check for this in the multixact case, because some
* locker transactions might still be running.
*/
UpdateXmaxHintBits(tuple->t_data, *buffer, xwait, relation);
}
}
/* By here, we're certain that we hold buffer exclusive lock again */
/*
* We may lock if previous xmax aborted, or if it committed but only
* locked the tuple without updating it; or if we didn't have to wait
* at all for whatever reason.
*/
if (!require_sleep ||
(tuple->t_data->t_infomask & HEAP_XMAX_INVALID) ||
HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_data->t_infomask) ||
HeapTupleHeaderIsOnlyLocked(tuple->t_data))
result = TM_Ok;
else if (!ItemPointerEquals(&tuple->t_self, &tuple->t_data->t_ctid) ||
HeapTupleHeaderIndicatesMovedPartitions(tuple->t_data))
result = TM_Updated;
else
result = TM_Deleted;
}
failed:
if (result != TM_Ok)
{
Assert(result == TM_SelfModified || result == TM_Updated ||
result == TM_Deleted || result == TM_WouldBlock);
Assert(!(tuple->t_data->t_infomask & HEAP_XMAX_INVALID));
Assert(result != TM_Updated ||
!ItemPointerEquals(&tuple->t_self, &tuple->t_data->t_ctid));
tmfd->ctid = tuple->t_data->t_ctid;
tmfd->xmax = HeapTupleHeaderGetUpdateXid(tuple->t_data);
if (result == TM_SelfModified)
tmfd->cmax = HeapTupleHeaderGetCmax(tuple->t_data);
else
tmfd->cmax = InvalidCommandId;
goto out_locked;
}
/*
* If we didn't pin the visibility map page and the page has become all
* visible while we were busy locking the buffer, or during some
* subsequent window during which we had it unlocked, we'll have to unlock
* and re-lock, to avoid holding the buffer lock across I/O. That's a bit
* unfortunate, especially since we'll now have to recheck whether the
* tuple has been locked or updated under us, but hopefully it won't
* happen very often.
*/
if (vmbuffer == InvalidBuffer && PageIsAllVisible(page))
{
LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
visibilitymap_pin(relation, block, &vmbuffer);
LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
goto l3;
}
xmax = HeapTupleHeaderGetRawXmax(tuple->t_data);
old_infomask = tuple->t_data->t_infomask;
/*
* If this is the first possibly-multixact-able operation in the current
* transaction, set my per-backend OldestMemberMXactId setting. We can be
* certain that the transaction will never become a member of any older
* MultiXactIds than that. (We have to do this even if we end up just
* using our own TransactionId below, since some other backend could
* incorporate our XID into a MultiXact immediately afterwards.)
*/
MultiXactIdSetOldestMember();
/*
* Compute the new xmax and infomask to store into the tuple. Note we do
* not modify the tuple just yet, because that would leave it in the wrong
* state if multixact.c elogs.
*/
compute_new_xmax_infomask(xmax, old_infomask, tuple->t_data->t_infomask2,
GetCurrentTransactionId(), mode, false,
&xid, &new_infomask, &new_infomask2);
START_CRIT_SECTION();
/*
* Store transaction information of xact locking the tuple.
*
* Note: Cmax is meaningless in this context, so don't set it; this avoids
* possibly generating a useless combo CID. Moreover, if we're locking a
* previously updated tuple, it's important to preserve the Cmax.
*
* Also reset the HOT UPDATE bit, but only if there's no update; otherwise
* we would break the HOT chain.
*/
tuple->t_data->t_infomask &= ~HEAP_XMAX_BITS;
tuple->t_data->t_infomask2 &= ~HEAP_KEYS_UPDATED;
tuple->t_data->t_infomask |= new_infomask;
tuple->t_data->t_infomask2 |= new_infomask2;
if (HEAP_XMAX_IS_LOCKED_ONLY(new_infomask))
HeapTupleHeaderClearHotUpdated(tuple->t_data);
HeapTupleHeaderSetXmax(tuple->t_data, xid);
/*
* Make sure there is no forward chain link in t_ctid. Note that in the
* cases where the tuple has been updated, we must not overwrite t_ctid,
* because it was set by the updater. Moreover, if the tuple has been
* updated, we need to follow the update chain to lock the new versions of
* the tuple as well.
*/
if (HEAP_XMAX_IS_LOCKED_ONLY(new_infomask))
tuple->t_data->t_ctid = *tid;
/* Clear only the all-frozen bit on visibility map if needed */
if (PageIsAllVisible(page) &&
visibilitymap_clear(relation, block, vmbuffer,
VISIBILITYMAP_ALL_FROZEN))
cleared_all_frozen = true;
MarkBufferDirty(*buffer);
/*
* XLOG stuff. You might think that we don't need an XLOG record because
* there is no state change worth restoring after a crash. You would be
* wrong however: we have just written either a TransactionId or a
* MultiXactId that may never have been seen on disk before, and we need
* to make sure that there are XLOG entries covering those ID numbers.
* Else the same IDs might be re-used after a crash, which would be
* disastrous if this page made it to disk before the crash. Essentially
* we have to enforce the WAL log-before-data rule even in this case.
* (Also, in a PITR log-shipping or 2PC environment, we have to have XLOG
* entries for everything anyway.)
*/
if (RelationNeedsWAL(relation))
{
xl_heap_lock xlrec;
XLogRecPtr recptr;
XLogBeginInsert();
XLogRegisterBuffer(0, *buffer, REGBUF_STANDARD);
xlrec.offnum = ItemPointerGetOffsetNumber(&tuple->t_self);
xlrec.locking_xid = xid;
xlrec.infobits_set = compute_infobits(new_infomask,
tuple->t_data->t_infomask2);
xlrec.flags = cleared_all_frozen ? XLH_LOCK_ALL_FROZEN_CLEARED : 0;
XLogRegisterData((char *) &xlrec, SizeOfHeapLock);
/* we don't decode row locks atm, so no need to log the origin */
recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_LOCK);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
result = TM_Ok;
out_locked:
LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
out_unlocked:
if (BufferIsValid(vmbuffer))
ReleaseBuffer(vmbuffer);
/*
* Don't update the visibility map here. Locking a tuple doesn't change
* visibility info.
*/
/*
* Now that we have successfully marked the tuple as locked, we can
* release the lmgr tuple lock, if we had it.
*/
if (have_tuple_lock)
UnlockTupleTuplock(relation, tid, mode);
return result;
}
/*
* Acquire heavyweight lock on the given tuple, in preparation for acquiring
* its normal, Xmax-based tuple lock.
*
* have_tuple_lock is an input and output parameter: on input, it indicates
* whether the lock has previously been acquired (and this function does
* nothing in that case). If this function returns success, have_tuple_lock
* has been flipped to true.
*
* Returns false if it was unable to obtain the lock; this can only happen if
* wait_policy is Skip.
*/
static bool
heap_acquire_tuplock(Relation relation, ItemPointer tid, LockTupleMode mode,
LockWaitPolicy wait_policy, bool *have_tuple_lock)
{
if (*have_tuple_lock)
return true;
switch (wait_policy)
{
case LockWaitBlock:
LockTupleTuplock(relation, tid, mode);
break;
case LockWaitSkip:
if (!ConditionalLockTupleTuplock(relation, tid, mode))
return false;
break;
case LockWaitError:
if (!ConditionalLockTupleTuplock(relation, tid, mode))
ereport(ERROR,
(errcode(ERRCODE_LOCK_NOT_AVAILABLE),
errmsg("could not obtain lock on row in relation \"%s\"",
RelationGetRelationName(relation))));
break;
}
*have_tuple_lock = true;
return true;
}
/*
* Given an original set of Xmax and infomask, and a transaction (identified by
* add_to_xmax) acquiring a new lock of some mode, compute the new Xmax and
* corresponding infomasks to use on the tuple.
*
* Note that this might have side effects such as creating a new MultiXactId.
*
* Most callers will have called HeapTupleSatisfiesUpdate before this function;
* that will have set the HEAP_XMAX_INVALID bit if the xmax was a MultiXactId
* but it was not running anymore. There is a race condition, which is that the
* MultiXactId may have finished since then, but that uncommon case is handled
* either here, or within MultiXactIdExpand.
*
* There is a similar race condition possible when the old xmax was a regular
* TransactionId. We test TransactionIdIsInProgress again just to narrow the
* window, but it's still possible to end up creating an unnecessary
* MultiXactId. Fortunately this is harmless.
*/
static void
compute_new_xmax_infomask(TransactionId xmax, uint16 old_infomask,
uint16 old_infomask2, TransactionId add_to_xmax,
LockTupleMode mode, bool is_update,
TransactionId *result_xmax, uint16 *result_infomask,
uint16 *result_infomask2)
{
TransactionId new_xmax;
uint16 new_infomask,
new_infomask2;
Assert(TransactionIdIsCurrentTransactionId(add_to_xmax));
l5:
new_infomask = 0;
new_infomask2 = 0;
if (old_infomask & HEAP_XMAX_INVALID)
{
/*
* No previous locker; we just insert our own TransactionId.
*
* Note that it's critical that this case be the first one checked,
* because there are several blocks below that come back to this one
* to implement certain optimizations; old_infomask might contain
* other dirty bits in those cases, but we don't really care.
*/
if (is_update)
{
new_xmax = add_to_xmax;
if (mode == LockTupleExclusive)
new_infomask2 |= HEAP_KEYS_UPDATED;
}
else
{
new_infomask |= HEAP_XMAX_LOCK_ONLY;
switch (mode)
{
case LockTupleKeyShare:
new_xmax = add_to_xmax;
new_infomask |= HEAP_XMAX_KEYSHR_LOCK;
break;
case LockTupleShare:
new_xmax = add_to_xmax;
new_infomask |= HEAP_XMAX_SHR_LOCK;
break;
case LockTupleNoKeyExclusive:
new_xmax = add_to_xmax;
new_infomask |= HEAP_XMAX_EXCL_LOCK;
break;
case LockTupleExclusive:
new_xmax = add_to_xmax;
new_infomask |= HEAP_XMAX_EXCL_LOCK;
new_infomask2 |= HEAP_KEYS_UPDATED;
break;
default:
new_xmax = InvalidTransactionId; /* silence compiler */
elog(ERROR, "invalid lock mode");
}
}
}
else if (old_infomask & HEAP_XMAX_IS_MULTI)
{
MultiXactStatus new_status;
/*
* Currently we don't allow XMAX_COMMITTED to be set for multis, so
* cross-check.
*/
Assert(!(old_infomask & HEAP_XMAX_COMMITTED));
/*
* A multixact together with LOCK_ONLY set but neither lock bit set
* (i.e. a pg_upgraded share locked tuple) cannot possibly be running
* anymore. This check is critical for databases upgraded by
* pg_upgrade; both MultiXactIdIsRunning and MultiXactIdExpand assume
* that such multis are never passed.
*/
if (HEAP_LOCKED_UPGRADED(old_infomask))
{
old_infomask &= ~HEAP_XMAX_IS_MULTI;
old_infomask |= HEAP_XMAX_INVALID;
goto l5;
}
/*
* If the XMAX is already a MultiXactId, then we need to expand it to
* include add_to_xmax; but if all the members were lockers and are
* all gone, we can do away with the IS_MULTI bit and just set
* add_to_xmax as the only locker/updater. If all lockers are gone
* and we have an updater that aborted, we can also do without a
* multi.
*
* The cost of doing GetMultiXactIdMembers would be paid by
* MultiXactIdExpand if we weren't to do this, so this check is not
* incurring extra work anyhow.
*/
if (!MultiXactIdIsRunning(xmax, HEAP_XMAX_IS_LOCKED_ONLY(old_infomask)))
{
if (HEAP_XMAX_IS_LOCKED_ONLY(old_infomask) ||
!TransactionIdDidCommit(MultiXactIdGetUpdateXid(xmax,
old_infomask)))
{
/*
* Reset these bits and restart; otherwise fall through to
* create a new multi below.
*/
old_infomask &= ~HEAP_XMAX_IS_MULTI;
old_infomask |= HEAP_XMAX_INVALID;
goto l5;
}
}
new_status = get_mxact_status_for_lock(mode, is_update);
new_xmax = MultiXactIdExpand((MultiXactId) xmax, add_to_xmax,
new_status);
GetMultiXactIdHintBits(new_xmax, &new_infomask, &new_infomask2);
}
else if (old_infomask & HEAP_XMAX_COMMITTED)
{
/*
* It's a committed update, so we need to preserve him as updater of
* the tuple.
*/
MultiXactStatus status;
MultiXactStatus new_status;
if (old_infomask2 & HEAP_KEYS_UPDATED)
status = MultiXactStatusUpdate;
else
status = MultiXactStatusNoKeyUpdate;
new_status = get_mxact_status_for_lock(mode, is_update);
/*
* since it's not running, it's obviously impossible for the old
* updater to be identical to the current one, so we need not check
* for that case as we do in the block above.
*/
new_xmax = MultiXactIdCreate(xmax, status, add_to_xmax, new_status);
GetMultiXactIdHintBits(new_xmax, &new_infomask, &new_infomask2);
}
else if (TransactionIdIsInProgress(xmax))
{
/*
* If the XMAX is a valid, in-progress TransactionId, then we need to
* create a new MultiXactId that includes both the old locker or
* updater and our own TransactionId.
*/
MultiXactStatus new_status;
MultiXactStatus old_status;
LockTupleMode old_mode;
if (HEAP_XMAX_IS_LOCKED_ONLY(old_infomask))
{
if (HEAP_XMAX_IS_KEYSHR_LOCKED(old_infomask))
old_status = MultiXactStatusForKeyShare;
else if (HEAP_XMAX_IS_SHR_LOCKED(old_infomask))
old_status = MultiXactStatusForShare;
else if (HEAP_XMAX_IS_EXCL_LOCKED(old_infomask))
{
if (old_infomask2 & HEAP_KEYS_UPDATED)
old_status = MultiXactStatusForUpdate;
else
old_status = MultiXactStatusForNoKeyUpdate;
}
else
{
/*
* LOCK_ONLY can be present alone only when a page has been
* upgraded by pg_upgrade. But in that case,
* TransactionIdIsInProgress() should have returned false. We
* assume it's no longer locked in this case.
*/
elog(WARNING, "LOCK_ONLY found for Xid in progress %u", xmax);
old_infomask |= HEAP_XMAX_INVALID;
old_infomask &= ~HEAP_XMAX_LOCK_ONLY;
goto l5;
}
}
else
{
/* it's an update, but which kind? */
if (old_infomask2 & HEAP_KEYS_UPDATED)
old_status = MultiXactStatusUpdate;
else
old_status = MultiXactStatusNoKeyUpdate;
}
old_mode = TUPLOCK_from_mxstatus(old_status);
/*
* If the lock to be acquired is for the same TransactionId as the
* existing lock, there's an optimization possible: consider only the
* strongest of both locks as the only one present, and restart.
*/
if (xmax == add_to_xmax)
{
/*
* Note that it's not possible for the original tuple to be
* updated: we wouldn't be here because the tuple would have been
* invisible and we wouldn't try to update it. As a subtlety,
* this code can also run when traversing an update chain to lock
* future versions of a tuple. But we wouldn't be here either,
* because the add_to_xmax would be different from the original
* updater.
*/
Assert(HEAP_XMAX_IS_LOCKED_ONLY(old_infomask));
/* acquire the strongest of both */
if (mode < old_mode)
mode = old_mode;
/* mustn't touch is_update */
old_infomask |= HEAP_XMAX_INVALID;
goto l5;
}
/* otherwise, just fall back to creating a new multixact */
new_status = get_mxact_status_for_lock(mode, is_update);
new_xmax = MultiXactIdCreate(xmax, old_status,
add_to_xmax, new_status);
GetMultiXactIdHintBits(new_xmax, &new_infomask, &new_infomask2);
}
else if (!HEAP_XMAX_IS_LOCKED_ONLY(old_infomask) &&
TransactionIdDidCommit(xmax))
{
/*
* It's a committed update, so we gotta preserve him as updater of the
* tuple.
*/
MultiXactStatus status;
MultiXactStatus new_status;
if (old_infomask2 & HEAP_KEYS_UPDATED)
status = MultiXactStatusUpdate;
else
status = MultiXactStatusNoKeyUpdate;
new_status = get_mxact_status_for_lock(mode, is_update);
/*
* since it's not running, it's obviously impossible for the old
* updater to be identical to the current one, so we need not check
* for that case as we do in the block above.
*/
new_xmax = MultiXactIdCreate(xmax, status, add_to_xmax, new_status);
GetMultiXactIdHintBits(new_xmax, &new_infomask, &new_infomask2);
}
else
{
/*
* Can get here iff the locking/updating transaction was running when
* the infomask was extracted from the tuple, but finished before
* TransactionIdIsInProgress got to run. Deal with it as if there was
* no locker at all in the first place.
*/
old_infomask |= HEAP_XMAX_INVALID;
goto l5;
}
*result_infomask = new_infomask;
*result_infomask2 = new_infomask2;
*result_xmax = new_xmax;
}
/*
* Subroutine for heap_lock_updated_tuple_rec.
*
* Given a hypothetical multixact status held by the transaction identified
* with the given xid, does the current transaction need to wait, fail, or can
* it continue if it wanted to acquire a lock of the given mode? "needwait"
* is set to true if waiting is necessary; if it can continue, then TM_Ok is
* returned. If the lock is already held by the current transaction, return
* TM_SelfModified. In case of a conflict with another transaction, a
* different HeapTupleSatisfiesUpdate return code is returned.
*
* The held status is said to be hypothetical because it might correspond to a
* lock held by a single Xid, i.e. not a real MultiXactId; we express it this
* way for simplicity of API.
*/
static TM_Result
test_lockmode_for_conflict(MultiXactStatus status, TransactionId xid,
LockTupleMode mode, HeapTuple tup,
bool *needwait)
{
MultiXactStatus wantedstatus;
*needwait = false;
wantedstatus = get_mxact_status_for_lock(mode, false);
/*
* Note: we *must* check TransactionIdIsInProgress before
* TransactionIdDidAbort/Commit; see comment at top of heapam_visibility.c
* for an explanation.
*/
if (TransactionIdIsCurrentTransactionId(xid))
{
/*
* The tuple has already been locked by our own transaction. This is
* very rare but can happen if multiple transactions are trying to
* lock an ancient version of the same tuple.
*/
return TM_SelfModified;
}
else if (TransactionIdIsInProgress(xid))
{
/*
* If the locking transaction is running, what we do depends on
* whether the lock modes conflict: if they do, then we must wait for
* it to finish; otherwise we can fall through to lock this tuple
* version without waiting.
*/
if (DoLockModesConflict(LOCKMODE_from_mxstatus(status),
LOCKMODE_from_mxstatus(wantedstatus)))
{
*needwait = true;
}
/*
* If we set needwait above, then this value doesn't matter;
* otherwise, this value signals to caller that it's okay to proceed.
*/
return TM_Ok;
}
else if (TransactionIdDidAbort(xid))
return TM_Ok;
else if (TransactionIdDidCommit(xid))
{
/*
* The other transaction committed. If it was only a locker, then the
* lock is completely gone now and we can return success; but if it
* was an update, then what we do depends on whether the two lock
* modes conflict. If they conflict, then we must report error to
* caller. But if they don't, we can fall through to allow the current
* transaction to lock the tuple.
*
* Note: the reason we worry about ISUPDATE here is because as soon as
* a transaction ends, all its locks are gone and meaningless, and
* thus we can ignore them; whereas its updates persist. In the
* TransactionIdIsInProgress case, above, we don't need to check
* because we know the lock is still "alive" and thus a conflict needs
* always be checked.
*/
if (!ISUPDATE_from_mxstatus(status))
return TM_Ok;
if (DoLockModesConflict(LOCKMODE_from_mxstatus(status),
LOCKMODE_from_mxstatus(wantedstatus)))
{
/* bummer */
if (!ItemPointerEquals(&tup->t_self, &tup->t_data->t_ctid) ||
HeapTupleHeaderIndicatesMovedPartitions(tup->t_data))
return TM_Updated;
else
return TM_Deleted;
}
return TM_Ok;
}
/* Not in progress, not aborted, not committed -- must have crashed */
return TM_Ok;
}
/*
* Recursive part of heap_lock_updated_tuple
*
* Fetch the tuple pointed to by tid in rel, and mark it as locked by the given
* xid with the given mode; if this tuple is updated, recurse to lock the new
* version as well.
*/
static TM_Result
heap_lock_updated_tuple_rec(Relation rel, ItemPointer tid, TransactionId xid,
LockTupleMode mode)
{
TM_Result result;
ItemPointerData tupid;
HeapTupleData mytup;
Buffer buf;
uint16 new_infomask,
new_infomask2,
old_infomask,
old_infomask2;
TransactionId xmax,
new_xmax;
TransactionId priorXmax = InvalidTransactionId;
bool cleared_all_frozen = false;
bool pinned_desired_page;
Buffer vmbuffer = InvalidBuffer;
BlockNumber block;
ItemPointerCopy(tid, &tupid);
for (;;)
{
new_infomask = 0;
new_xmax = InvalidTransactionId;
block = ItemPointerGetBlockNumber(&tupid);
ItemPointerCopy(&tupid, &(mytup.t_self));
if (!heap_fetch(rel, SnapshotAny, &mytup, &buf))
{
/*
* if we fail to find the updated version of the tuple, it's
* because it was vacuumed/pruned away after its creator
* transaction aborted. So behave as if we got to the end of the
* chain, and there's no further tuple to lock: return success to
* caller.
*/
result = TM_Ok;
goto out_unlocked;
}
l4:
CHECK_FOR_INTERRUPTS();
/*
* Before locking the buffer, pin the visibility map page if it
* appears to be necessary. Since we haven't got the lock yet,
* someone else might be in the middle of changing this, so we'll need
* to recheck after we have the lock.
*/
if (PageIsAllVisible(BufferGetPage(buf)))
{
visibilitymap_pin(rel, block, &vmbuffer);
pinned_desired_page = true;
}
else
pinned_desired_page = false;
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
/*
* If we didn't pin the visibility map page and the page has become
* all visible while we were busy locking the buffer, we'll have to
* unlock and re-lock, to avoid holding the buffer lock across I/O.
* That's a bit unfortunate, but hopefully shouldn't happen often.
*
* Note: in some paths through this function, we will reach here
* holding a pin on a vm page that may or may not be the one matching
* this page. If this page isn't all-visible, we won't use the vm
* page, but we hold onto such a pin till the end of the function.
*/
if (!pinned_desired_page && PageIsAllVisible(BufferGetPage(buf)))
{
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
visibilitymap_pin(rel, block, &vmbuffer);
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
}
/*
* Check the tuple XMIN against prior XMAX, if any. If we reached the
* end of the chain, we're done, so return success.
*/
if (TransactionIdIsValid(priorXmax) &&
!TransactionIdEquals(HeapTupleHeaderGetXmin(mytup.t_data),
priorXmax))
{
result = TM_Ok;
goto out_locked;
}
/*
* Also check Xmin: if this tuple was created by an aborted
* (sub)transaction, then we already locked the last live one in the
* chain, thus we're done, so return success.
*/
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(mytup.t_data)))
{
result = TM_Ok;
goto out_locked;
}
old_infomask = mytup.t_data->t_infomask;
old_infomask2 = mytup.t_data->t_infomask2;
xmax = HeapTupleHeaderGetRawXmax(mytup.t_data);
/*
* If this tuple version has been updated or locked by some concurrent
* transaction(s), what we do depends on whether our lock mode
* conflicts with what those other transactions hold, and also on the
* status of them.
*/
if (!(old_infomask & HEAP_XMAX_INVALID))
{
TransactionId rawxmax;
bool needwait;
rawxmax = HeapTupleHeaderGetRawXmax(mytup.t_data);
if (old_infomask & HEAP_XMAX_IS_MULTI)
{
int nmembers;
int i;
MultiXactMember *members;
/*
* We don't need a test for pg_upgrade'd tuples: this is only
* applied to tuples after the first in an update chain. Said
* first tuple in the chain may well be locked-in-9.2-and-
* pg_upgraded, but that one was already locked by our caller,
* not us; and any subsequent ones cannot be because our
* caller must necessarily have obtained a snapshot later than
* the pg_upgrade itself.
*/
Assert(!HEAP_LOCKED_UPGRADED(mytup.t_data->t_infomask));
nmembers = GetMultiXactIdMembers(rawxmax, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(old_infomask));
for (i = 0; i < nmembers; i++)
{
result = test_lockmode_for_conflict(members[i].status,
members[i].xid,
mode,
&mytup,
&needwait);
/*
* If the tuple was already locked by ourselves in a
* previous iteration of this (say heap_lock_tuple was
* forced to restart the locking loop because of a change
* in xmax), then we hold the lock already on this tuple
* version and we don't need to do anything; and this is
* not an error condition either. We just need to skip
* this tuple and continue locking the next version in the
* update chain.
*/
if (result == TM_SelfModified)
{
pfree(members);
goto next;
}
if (needwait)
{
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
XactLockTableWait(members[i].xid, rel,
&mytup.t_self,
XLTW_LockUpdated);
pfree(members);
goto l4;
}
if (result != TM_Ok)
{
pfree(members);
goto out_locked;
}
}
if (members)
pfree(members);
}
else
{
MultiXactStatus status;
/*
* For a non-multi Xmax, we first need to compute the
* corresponding MultiXactStatus by using the infomask bits.
*/
if (HEAP_XMAX_IS_LOCKED_ONLY(old_infomask))
{
if (HEAP_XMAX_IS_KEYSHR_LOCKED(old_infomask))
status = MultiXactStatusForKeyShare;
else if (HEAP_XMAX_IS_SHR_LOCKED(old_infomask))
status = MultiXactStatusForShare;
else if (HEAP_XMAX_IS_EXCL_LOCKED(old_infomask))
{
if (old_infomask2 & HEAP_KEYS_UPDATED)
status = MultiXactStatusForUpdate;
else
status = MultiXactStatusForNoKeyUpdate;
}
else
{
/*
* LOCK_ONLY present alone (a pg_upgraded tuple marked
* as share-locked in the old cluster) shouldn't be
* seen in the middle of an update chain.
*/
elog(ERROR, "invalid lock status in tuple");
}
}
else
{
/* it's an update, but which kind? */
if (old_infomask2 & HEAP_KEYS_UPDATED)
status = MultiXactStatusUpdate;
else
status = MultiXactStatusNoKeyUpdate;
}
result = test_lockmode_for_conflict(status, rawxmax, mode,
&mytup, &needwait);
/*
* If the tuple was already locked by ourselves in a previous
* iteration of this (say heap_lock_tuple was forced to
* restart the locking loop because of a change in xmax), then
* we hold the lock already on this tuple version and we don't
* need to do anything; and this is not an error condition
* either. We just need to skip this tuple and continue
* locking the next version in the update chain.
*/
if (result == TM_SelfModified)
goto next;
if (needwait)
{
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
XactLockTableWait(rawxmax, rel, &mytup.t_self,
XLTW_LockUpdated);
goto l4;
}
if (result != TM_Ok)
{
goto out_locked;
}
}
}
/* compute the new Xmax and infomask values for the tuple ... */
compute_new_xmax_infomask(xmax, old_infomask, mytup.t_data->t_infomask2,
xid, mode, false,
&new_xmax, &new_infomask, &new_infomask2);
if (PageIsAllVisible(BufferGetPage(buf)) &&
visibilitymap_clear(rel, block, vmbuffer,
VISIBILITYMAP_ALL_FROZEN))
cleared_all_frozen = true;
START_CRIT_SECTION();
/* ... and set them */
HeapTupleHeaderSetXmax(mytup.t_data, new_xmax);
mytup.t_data->t_infomask &= ~HEAP_XMAX_BITS;
mytup.t_data->t_infomask2 &= ~HEAP_KEYS_UPDATED;
mytup.t_data->t_infomask |= new_infomask;
mytup.t_data->t_infomask2 |= new_infomask2;
MarkBufferDirty(buf);
/* XLOG stuff */
if (RelationNeedsWAL(rel))
{
xl_heap_lock_updated xlrec;
XLogRecPtr recptr;
Page page = BufferGetPage(buf);
XLogBeginInsert();
XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
xlrec.offnum = ItemPointerGetOffsetNumber(&mytup.t_self);
xlrec.xmax = new_xmax;
xlrec.infobits_set = compute_infobits(new_infomask, new_infomask2);
xlrec.flags =
cleared_all_frozen ? XLH_LOCK_ALL_FROZEN_CLEARED : 0;
XLogRegisterData((char *) &xlrec, SizeOfHeapLockUpdated);
recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_LOCK_UPDATED);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
next:
/* if we find the end of update chain, we're done. */
if (mytup.t_data->t_infomask & HEAP_XMAX_INVALID ||
HeapTupleHeaderIndicatesMovedPartitions(mytup.t_data) ||
ItemPointerEquals(&mytup.t_self, &mytup.t_data->t_ctid) ||
HeapTupleHeaderIsOnlyLocked(mytup.t_data))
{
result = TM_Ok;
goto out_locked;
}
/* tail recursion */
priorXmax = HeapTupleHeaderGetUpdateXid(mytup.t_data);
ItemPointerCopy(&(mytup.t_data->t_ctid), &tupid);
UnlockReleaseBuffer(buf);
}
result = TM_Ok;
out_locked:
UnlockReleaseBuffer(buf);
out_unlocked:
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
return result;
}
/*
* heap_lock_updated_tuple
* Follow update chain when locking an updated tuple, acquiring locks (row
* marks) on the updated versions.
*
* The initial tuple is assumed to be already locked.
*
* This function doesn't check visibility, it just unconditionally marks the
* tuple(s) as locked. If any tuple in the updated chain is being deleted
* concurrently (or updated with the key being modified), sleep until the
* transaction doing it is finished.
*
* Note that we don't acquire heavyweight tuple locks on the tuples we walk
* when we have to wait for other transactions to release them, as opposed to
* what heap_lock_tuple does. The reason is that having more than one
* transaction walking the chain is probably uncommon enough that risk of
* starvation is not likely: one of the preconditions for being here is that
* the snapshot in use predates the update that created this tuple (because we
* started at an earlier version of the tuple), but at the same time such a
* transaction cannot be using repeatable read or serializable isolation
* levels, because that would lead to a serializability failure.
*/
static TM_Result
heap_lock_updated_tuple(Relation rel, HeapTuple tuple, ItemPointer ctid,
TransactionId xid, LockTupleMode mode)
{
/*
* If the tuple has not been updated, or has moved into another partition
* (effectively a delete) stop here.
*/
if (!HeapTupleHeaderIndicatesMovedPartitions(tuple->t_data) &&
!ItemPointerEquals(&tuple->t_self, ctid))
{
/*
* If this is the first possibly-multixact-able operation in the
* current transaction, set my per-backend OldestMemberMXactId
* setting. We can be certain that the transaction will never become a
* member of any older MultiXactIds than that. (We have to do this
* even if we end up just using our own TransactionId below, since
* some other backend could incorporate our XID into a MultiXact
* immediately afterwards.)
*/
MultiXactIdSetOldestMember();
return heap_lock_updated_tuple_rec(rel, ctid, xid, mode);
}
/* nothing to lock */
return TM_Ok;
}
/*
* heap_finish_speculative - mark speculative insertion as successful
*
* To successfully finish a speculative insertion we have to clear speculative
* token from tuple. To do so the t_ctid field, which will contain a
* speculative token value, is modified in place to point to the tuple itself,
* which is characteristic of a newly inserted ordinary tuple.
*
* NB: It is not ok to commit without either finishing or aborting a
* speculative insertion. We could treat speculative tuples of committed
* transactions implicitly as completed, but then we would have to be prepared
* to deal with speculative tokens on committed tuples. That wouldn't be
* difficult - no-one looks at the ctid field of a tuple with invalid xmax -
* but clearing the token at completion isn't very expensive either.
* An explicit confirmation WAL record also makes logical decoding simpler.
*/
void
heap_finish_speculative(Relation relation, ItemPointer tid)
{
Buffer buffer;
Page page;
OffsetNumber offnum;
ItemId lp = NULL;
HeapTupleHeader htup;
buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
offnum = ItemPointerGetOffsetNumber(tid);
if (PageGetMaxOffsetNumber(page) >= offnum)
lp = PageGetItemId(page, offnum);
if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp))
elog(ERROR, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
/* SpecTokenOffsetNumber should be distinguishable from any real offset */
StaticAssertStmt(MaxOffsetNumber < SpecTokenOffsetNumber,
"invalid speculative token constant");
/* NO EREPORT(ERROR) from here till changes are logged */
START_CRIT_SECTION();
Assert(HeapTupleHeaderIsSpeculative(htup));
MarkBufferDirty(buffer);
/*
* Replace the speculative insertion token with a real t_ctid, pointing to
* itself like it does on regular tuples.
*/
htup->t_ctid = *tid;
/* XLOG stuff */
if (RelationNeedsWAL(relation))
{
xl_heap_confirm xlrec;
XLogRecPtr recptr;
xlrec.offnum = ItemPointerGetOffsetNumber(tid);
XLogBeginInsert();
/* We want the same filtering on this as on a plain insert */
XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN);
XLogRegisterData((char *) &xlrec, SizeOfHeapConfirm);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_CONFIRM);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
UnlockReleaseBuffer(buffer);
}
/*
* heap_abort_speculative - kill a speculatively inserted tuple
*
* Marks a tuple that was speculatively inserted in the same command as dead,
* by setting its xmin as invalid. That makes it immediately appear as dead
* to all transactions, including our own. In particular, it makes
* HeapTupleSatisfiesDirty() regard the tuple as dead, so that another backend
* inserting a duplicate key value won't unnecessarily wait for our whole
* transaction to finish (it'll just wait for our speculative insertion to
* finish).
*
* Killing the tuple prevents "unprincipled deadlocks", which are deadlocks
* that arise due to a mutual dependency that is not user visible. By
* definition, unprincipled deadlocks cannot be prevented by the user
* reordering lock acquisition in client code, because the implementation level
* lock acquisitions are not under the user's direct control. If speculative
* inserters did not take this precaution, then under high concurrency they
* could deadlock with each other, which would not be acceptable.
*
* This is somewhat redundant with heap_delete, but we prefer to have a
* dedicated routine with stripped down requirements. Note that this is also
* used to delete the TOAST tuples created during speculative insertion.
*
* This routine does not affect logical decoding as it only looks at
* confirmation records.
*/
void
heap_abort_speculative(Relation relation, ItemPointer tid)
{
TransactionId xid = GetCurrentTransactionId();
ItemId lp;
HeapTupleData tp;
Page page;
BlockNumber block;
Buffer buffer;
Assert(ItemPointerIsValid(tid));
block = ItemPointerGetBlockNumber(tid);
buffer = ReadBuffer(relation, block);
page = BufferGetPage(buffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
/*
* Page can't be all visible, we just inserted into it, and are still
* running.
*/
Assert(!PageIsAllVisible(page));
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid));
Assert(ItemIdIsNormal(lp));
tp.t_tableOid = RelationGetRelid(relation);
tp.t_data = (HeapTupleHeader) PageGetItem(page, lp);
tp.t_len = ItemIdGetLength(lp);
tp.t_self = *tid;
/*
* Sanity check that the tuple really is a speculatively inserted tuple,
* inserted by us.
*/
if (tp.t_data->t_choice.t_heap.t_xmin != xid)
elog(ERROR, "attempted to kill a tuple inserted by another transaction");
if (!(IsToastRelation(relation) || HeapTupleHeaderIsSpeculative(tp.t_data)))
elog(ERROR, "attempted to kill a non-speculative tuple");
Assert(!HeapTupleHeaderIsHeapOnly(tp.t_data));
/*
* No need to check for serializable conflicts here. There is never a
* need for a combocid, either. No need to extract replica identity, or
* do anything special with infomask bits.
*/
START_CRIT_SECTION();
/*
* The tuple will become DEAD immediately. Flag that this page
* immediately is a candidate for pruning by setting xmin to
* RecentGlobalXmin. That's not pretty, but it doesn't seem worth
* inventing a nicer API for this.
*/
Assert(TransactionIdIsValid(RecentGlobalXmin));
PageSetPrunable(page, RecentGlobalXmin);
/* store transaction information of xact deleting the tuple */
tp.t_data->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
tp.t_data->t_infomask2 &= ~HEAP_KEYS_UPDATED;
/*
* Set the tuple header xmin to InvalidTransactionId. This makes the
* tuple immediately invisible everyone. (In particular, to any
* transactions waiting on the speculative token, woken up later.)
*/
HeapTupleHeaderSetXmin(tp.t_data, InvalidTransactionId);
/* Clear the speculative insertion token too */
tp.t_data->t_ctid = tp.t_self;
MarkBufferDirty(buffer);
/*
* XLOG stuff
*
* The WAL records generated here match heap_delete(). The same recovery
* routines are used.
*/
if (RelationNeedsWAL(relation))
{
xl_heap_delete xlrec;
XLogRecPtr recptr;
xlrec.flags = XLH_DELETE_IS_SUPER;
xlrec.infobits_set = compute_infobits(tp.t_data->t_infomask,
tp.t_data->t_infomask2);
xlrec.offnum = ItemPointerGetOffsetNumber(&tp.t_self);
xlrec.xmax = xid;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapDelete);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
/* No replica identity & replication origin logged */
recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_DELETE);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
if (HeapTupleHasExternal(&tp))
{
Assert(!IsToastRelation(relation));
toast_delete(relation, &tp, true);
}
/*
* Never need to mark tuple for invalidation, since catalogs don't support
* speculative insertion
*/
/* Now we can release the buffer */
ReleaseBuffer(buffer);
/* count deletion, as we counted the insertion too */
pgstat_count_heap_delete(relation);
}
/*
* heap_inplace_update - update a tuple "in place" (ie, overwrite it)
*
* Overwriting violates both MVCC and transactional safety, so the uses
* of this function in Postgres are extremely limited. Nonetheless we
* find some places to use it.
*
* The tuple cannot change size, and therefore it's reasonable to assume
* that its null bitmap (if any) doesn't change either. So we just
* overwrite the data portion of the tuple without touching the null
* bitmap or any of the header fields.
*
* tuple is an in-memory tuple structure containing the data to be written
* over the target tuple. Also, tuple->t_self identifies the target tuple.
*/
void
heap_inplace_update(Relation relation, HeapTuple tuple)
{
Buffer buffer;
Page page;
OffsetNumber offnum;
ItemId lp = NULL;
HeapTupleHeader htup;
uint32 oldlen;
uint32 newlen;
/*
* For now, parallel operations are required to be strictly read-only.
* Unlike a regular update, this should never create a combo CID, so it
* might be possible to relax this restriction, but not without more
* thought and testing. It's not clear that it would be useful, anyway.
*/
if (IsInParallelMode())
ereport(ERROR,
(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
errmsg("cannot update tuples during a parallel operation")));
buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&(tuple->t_self)));
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
offnum = ItemPointerGetOffsetNumber(&(tuple->t_self));
if (PageGetMaxOffsetNumber(page) >= offnum)
lp = PageGetItemId(page, offnum);
if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp))
elog(ERROR, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
oldlen = ItemIdGetLength(lp) - htup->t_hoff;
newlen = tuple->t_len - tuple->t_data->t_hoff;
if (oldlen != newlen || htup->t_hoff != tuple->t_data->t_hoff)
elog(ERROR, "wrong tuple length");
/* NO EREPORT(ERROR) from here till changes are logged */
START_CRIT_SECTION();
memcpy((char *) htup + htup->t_hoff,
(char *) tuple->t_data + tuple->t_data->t_hoff,
newlen);
MarkBufferDirty(buffer);
/* XLOG stuff */
if (RelationNeedsWAL(relation))
{
xl_heap_inplace xlrec;
XLogRecPtr recptr;
xlrec.offnum = ItemPointerGetOffsetNumber(&tuple->t_self);
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapInplace);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
XLogRegisterBufData(0, (char *) htup + htup->t_hoff, newlen);
/* inplace updates aren't decoded atm, don't log the origin */
recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_INPLACE);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
UnlockReleaseBuffer(buffer);
/*
* Send out shared cache inval if necessary. Note that because we only
* pass the new version of the tuple, this mustn't be used for any
* operations that could change catcache lookup keys. But we aren't
* bothering with index updates either, so that's true a fortiori.
*/
if (!IsBootstrapProcessingMode())
CacheInvalidateHeapTuple(relation, tuple, NULL);
}
#define FRM_NOOP 0x0001
#define FRM_INVALIDATE_XMAX 0x0002
#define FRM_RETURN_IS_XID 0x0004
#define FRM_RETURN_IS_MULTI 0x0008
#define FRM_MARK_COMMITTED 0x0010
/*
* FreezeMultiXactId
* Determine what to do during freezing when a tuple is marked by a
* MultiXactId.
*
* NB -- this might have the side-effect of creating a new MultiXactId!
*
* "flags" is an output value; it's used to tell caller what to do on return.
* Possible flags are:
* FRM_NOOP
* don't do anything -- keep existing Xmax
* FRM_INVALIDATE_XMAX
* mark Xmax as InvalidTransactionId and set XMAX_INVALID flag.
* FRM_RETURN_IS_XID
* The Xid return value is a single update Xid to set as xmax.
* FRM_MARK_COMMITTED
* Xmax can be marked as HEAP_XMAX_COMMITTED
* FRM_RETURN_IS_MULTI
* The return value is a new MultiXactId to set as new Xmax.
* (caller must obtain proper infomask bits using GetMultiXactIdHintBits)
*/
static TransactionId
FreezeMultiXactId(MultiXactId multi, uint16 t_infomask,
TransactionId relfrozenxid, TransactionId relminmxid,
TransactionId cutoff_xid, MultiXactId cutoff_multi,
uint16 *flags)
{
TransactionId xid = InvalidTransactionId;
int i;
MultiXactMember *members;
int nmembers;
bool need_replace;
int nnewmembers;
MultiXactMember *newmembers;
bool has_lockers;
TransactionId update_xid;
bool update_committed;
*flags = 0;
/* We should only be called in Multis */
Assert(t_infomask & HEAP_XMAX_IS_MULTI);
if (!MultiXactIdIsValid(multi) ||
HEAP_LOCKED_UPGRADED(t_infomask))
{
/* Ensure infomask bits are appropriately set/reset */
*flags |= FRM_INVALIDATE_XMAX;
return InvalidTransactionId;
}
else if (MultiXactIdPrecedes(multi, relminmxid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("found multixact %u from before relminmxid %u",
multi, relminmxid)));
else if (MultiXactIdPrecedes(multi, cutoff_multi))
{
/*
* This old multi cannot possibly have members still running, but
* verify just in case. If it was a locker only, it can be removed
* without any further consideration; but if it contained an update,
* we might need to preserve it.
*/
if (MultiXactIdIsRunning(multi,
HEAP_XMAX_IS_LOCKED_ONLY(t_infomask)))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("multixact %u from before cutoff %u found to be still running",
multi, cutoff_multi)));
if (HEAP_XMAX_IS_LOCKED_ONLY(t_infomask))
{
*flags |= FRM_INVALIDATE_XMAX;
xid = InvalidTransactionId; /* not strictly necessary */
}
else
{
/* replace multi by update xid */
xid = MultiXactIdGetUpdateXid(multi, t_infomask);
/* wasn't only a lock, xid needs to be valid */
Assert(TransactionIdIsValid(xid));
if (TransactionIdPrecedes(xid, relfrozenxid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("found update xid %u from before relfrozenxid %u",
xid, relfrozenxid)));
/*
* If the xid is older than the cutoff, it has to have aborted,
* otherwise the tuple would have gotten pruned away.
*/
if (TransactionIdPrecedes(xid, cutoff_xid))
{
if (TransactionIdDidCommit(xid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("cannot freeze committed update xid %u", xid)));
*flags |= FRM_INVALIDATE_XMAX;
xid = InvalidTransactionId; /* not strictly necessary */
}
else
{
*flags |= FRM_RETURN_IS_XID;
}
}
return xid;
}
/*
* This multixact might have or might not have members still running, but
* we know it's valid and is newer than the cutoff point for multis.
* However, some member(s) of it may be below the cutoff for Xids, so we
* need to walk the whole members array to figure out what to do, if
* anything.
*/
nmembers =
GetMultiXactIdMembers(multi, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(t_infomask));
if (nmembers <= 0)
{
/* Nothing worth keeping */
*flags |= FRM_INVALIDATE_XMAX;
return InvalidTransactionId;
}
/* is there anything older than the cutoff? */
need_replace = false;
for (i = 0; i < nmembers; i++)
{
if (TransactionIdPrecedes(members[i].xid, cutoff_xid))
{
need_replace = true;
break;
}
}
/*
* In the simplest case, there is no member older than the cutoff; we can
* keep the existing MultiXactId as is.
*/
if (!need_replace)
{
*flags |= FRM_NOOP;
pfree(members);
return InvalidTransactionId;
}
/*
* If the multi needs to be updated, figure out which members do we need
* to keep.
*/
nnewmembers = 0;
newmembers = palloc(sizeof(MultiXactMember) * nmembers);
has_lockers = false;
update_xid = InvalidTransactionId;
update_committed = false;
for (i = 0; i < nmembers; i++)
{
/*
* Determine whether to keep this member or ignore it.
*/
if (ISUPDATE_from_mxstatus(members[i].status))
{
TransactionId xid = members[i].xid;
Assert(TransactionIdIsValid(xid));
if (TransactionIdPrecedes(xid, relfrozenxid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("found update xid %u from before relfrozenxid %u",
xid, relfrozenxid)));
/*
* It's an update; should we keep it? If the transaction is known
* aborted or crashed then it's okay to ignore it, otherwise not.
* Note that an updater older than cutoff_xid cannot possibly be
* committed, because HeapTupleSatisfiesVacuum would have returned
* HEAPTUPLE_DEAD and we would not be trying to freeze the tuple.
*
* As with all tuple visibility routines, it's critical to test
* TransactionIdIsInProgress before TransactionIdDidCommit,
* because of race conditions explained in detail in
* heapam_visibility.c.
*/
if (TransactionIdIsCurrentTransactionId(xid) ||
TransactionIdIsInProgress(xid))
{
Assert(!TransactionIdIsValid(update_xid));
update_xid = xid;
}
else if (TransactionIdDidCommit(xid))
{
/*
* The transaction committed, so we can tell caller to set
* HEAP_XMAX_COMMITTED. (We can only do this because we know
* the transaction is not running.)
*/
Assert(!TransactionIdIsValid(update_xid));
update_committed = true;
update_xid = xid;
}
else
{
/*
* Not in progress, not committed -- must be aborted or
* crashed; we can ignore it.
*/
}
/*
* Since the tuple wasn't marked HEAPTUPLE_DEAD by vacuum, the
* update Xid cannot possibly be older than the xid cutoff. The
* presence of such a tuple would cause corruption, so be paranoid
* and check.
*/
if (TransactionIdIsValid(update_xid) &&
TransactionIdPrecedes(update_xid, cutoff_xid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("found update xid %u from before xid cutoff %u",
update_xid, cutoff_xid)));
/*
* If we determined that it's an Xid corresponding to an update
* that must be retained, additionally add it to the list of
* members of the new Multi, in case we end up using that. (We
* might still decide to use only an update Xid and not a multi,
* but it's easier to maintain the list as we walk the old members
* list.)
*/
if (TransactionIdIsValid(update_xid))
newmembers[nnewmembers++] = members[i];
}
else
{
/* We only keep lockers if they are still running */
if (TransactionIdIsCurrentTransactionId(members[i].xid) ||
TransactionIdIsInProgress(members[i].xid))
{
/* running locker cannot possibly be older than the cutoff */
Assert(!TransactionIdPrecedes(members[i].xid, cutoff_xid));
newmembers[nnewmembers++] = members[i];
has_lockers = true;
}
}
}
pfree(members);
if (nnewmembers == 0)
{
/* nothing worth keeping!? Tell caller to remove the whole thing */
*flags |= FRM_INVALIDATE_XMAX;
xid = InvalidTransactionId;
}
else if (TransactionIdIsValid(update_xid) && !has_lockers)
{
/*
* If there's a single member and it's an update, pass it back alone
* without creating a new Multi. (XXX we could do this when there's a
* single remaining locker, too, but that would complicate the API too
* much; moreover, the case with the single updater is more
* interesting, because those are longer-lived.)
*/
Assert(nnewmembers == 1);
*flags |= FRM_RETURN_IS_XID;
if (update_committed)
*flags |= FRM_MARK_COMMITTED;
xid = update_xid;
}
else
{
/*
* Create a new multixact with the surviving members of the previous
* one, to set as new Xmax in the tuple.
*/
xid = MultiXactIdCreateFromMembers(nnewmembers, newmembers);
*flags |= FRM_RETURN_IS_MULTI;
}
pfree(newmembers);
return xid;
}
/*
* heap_prepare_freeze_tuple
*
* Check to see whether any of the XID fields of a tuple (xmin, xmax, xvac)
* are older than the specified cutoff XID and cutoff MultiXactId. If so,
* setup enough state (in the *frz output argument) to later execute and
* WAL-log what we would need to do, and return true. Return false if nothing
* is to be changed. In addition, set *totally_frozen_p to true if the tuple
* will be totally frozen after these operations are performed and false if
* more freezing will eventually be required.
*
* Caller is responsible for setting the offset field, if appropriate.
*
* It is assumed that the caller has checked the tuple with
* HeapTupleSatisfiesVacuum() and determined that it is not HEAPTUPLE_DEAD
* (else we should be removing the tuple, not freezing it).
*
* NB: cutoff_xid *must* be <= the current global xmin, to ensure that any
* XID older than it could neither be running nor seen as running by any
* open transaction. This ensures that the replacement will not change
* anyone's idea of the tuple state.
* Similarly, cutoff_multi must be less than or equal to the smallest
* MultiXactId used by any transaction currently open.
*
* If the tuple is in a shared buffer, caller must hold an exclusive lock on
* that buffer.
*
* NB: It is not enough to set hint bits to indicate something is
* committed/invalid -- they might not be set on a standby, or after crash
* recovery. We really need to remove old xids.
*/
bool
heap_prepare_freeze_tuple(HeapTupleHeader tuple,
TransactionId relfrozenxid, TransactionId relminmxid,
TransactionId cutoff_xid, TransactionId cutoff_multi,
xl_heap_freeze_tuple *frz, bool *totally_frozen_p)
{
bool changed = false;
bool xmax_already_frozen = false;
bool xmin_frozen;
bool freeze_xmax;
TransactionId xid;
frz->frzflags = 0;
frz->t_infomask2 = tuple->t_infomask2;
frz->t_infomask = tuple->t_infomask;
frz->xmax = HeapTupleHeaderGetRawXmax(tuple);
/*
* Process xmin. xmin_frozen has two slightly different meanings: in the
* !XidIsNormal case, it means "the xmin doesn't need any freezing" (it's
* already a permanent value), while in the block below it is set true to
* mean "xmin won't need freezing after what we do to it here" (false
* otherwise). In both cases we're allowed to set totally_frozen, as far
* as xmin is concerned.
*/
xid = HeapTupleHeaderGetXmin(tuple);
if (!TransactionIdIsNormal(xid))
xmin_frozen = true;
else
{
if (TransactionIdPrecedes(xid, relfrozenxid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("found xmin %u from before relfrozenxid %u",
xid, relfrozenxid)));
xmin_frozen = TransactionIdPrecedes(xid, cutoff_xid);
if (xmin_frozen)
{
if (!TransactionIdDidCommit(xid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("uncommitted xmin %u from before xid cutoff %u needs to be frozen",
xid, cutoff_xid)));
frz->t_infomask |= HEAP_XMIN_FROZEN;
changed = true;
xmin_frozen = true;
}
}
/*
* Process xmax. To thoroughly examine the current Xmax value we need to
* resolve a MultiXactId to its member Xids, in case some of them are
* below the given cutoff for Xids. In that case, those values might need
* freezing, too. Also, if a multi needs freezing, we cannot simply take
* it out --- if there's a live updater Xid, it needs to be kept.
*
* Make sure to keep heap_tuple_needs_freeze in sync with this.
*/
xid = HeapTupleHeaderGetRawXmax(tuple);
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
{
TransactionId newxmax;
uint16 flags;
newxmax = FreezeMultiXactId(xid, tuple->t_infomask,
relfrozenxid, relminmxid,
cutoff_xid, cutoff_multi, &flags);
freeze_xmax = (flags & FRM_INVALIDATE_XMAX);
if (flags & FRM_RETURN_IS_XID)
{
/*
* NB -- some of these transformations are only valid because we
* know the return Xid is a tuple updater (i.e. not merely a
* locker.) Also note that the only reason we don't explicitly
* worry about HEAP_KEYS_UPDATED is because it lives in
* t_infomask2 rather than t_infomask.
*/
frz->t_infomask &= ~HEAP_XMAX_BITS;
frz->xmax = newxmax;
if (flags & FRM_MARK_COMMITTED)
frz->t_infomask |= HEAP_XMAX_COMMITTED;
changed = true;
}
else if (flags & FRM_RETURN_IS_MULTI)
{
uint16 newbits;
uint16 newbits2;
/*
* We can't use GetMultiXactIdHintBits directly on the new multi
* here; that routine initializes the masks to all zeroes, which
* would lose other bits we need. Doing it this way ensures all
* unrelated bits remain untouched.
*/
frz->t_infomask &= ~HEAP_XMAX_BITS;
frz->t_infomask2 &= ~HEAP_KEYS_UPDATED;
GetMultiXactIdHintBits(newxmax, &newbits, &newbits2);
frz->t_infomask |= newbits;
frz->t_infomask2 |= newbits2;
frz->xmax = newxmax;
changed = true;
}
}
else if (TransactionIdIsNormal(xid))
{
if (TransactionIdPrecedes(xid, relfrozenxid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("found xmax %u from before relfrozenxid %u",
xid, relfrozenxid)));
if (TransactionIdPrecedes(xid, cutoff_xid))
{
/*
* If we freeze xmax, make absolutely sure that it's not an XID
* that is important. (Note, a lock-only xmax can be removed
* independent of committedness, since a committed lock holder has
* released the lock).
*/
if (!HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask) &&
TransactionIdDidCommit(xid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("cannot freeze committed xmax %u",
xid)));
freeze_xmax = true;
}
else
freeze_xmax = false;
}
else if ((tuple->t_infomask & HEAP_XMAX_INVALID) ||
!TransactionIdIsValid(HeapTupleHeaderGetRawXmax(tuple)))
{
freeze_xmax = false;
xmax_already_frozen = true;
}
else
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("found xmax %u (infomask 0x%04x) not frozen, not multi, not normal",
xid, tuple->t_infomask)));
if (freeze_xmax)
{
Assert(!xmax_already_frozen);
frz->xmax = InvalidTransactionId;
/*
* The tuple might be marked either XMAX_INVALID or XMAX_COMMITTED +
* LOCKED. Normalize to INVALID just to be sure no one gets confused.
* Also get rid of the HEAP_KEYS_UPDATED bit.
*/
frz->t_infomask &= ~HEAP_XMAX_BITS;
frz->t_infomask |= HEAP_XMAX_INVALID;
frz->t_infomask2 &= ~HEAP_HOT_UPDATED;
frz->t_infomask2 &= ~HEAP_KEYS_UPDATED;
changed = true;
}
/*
* Old-style VACUUM FULL is gone, but we have to keep this code as long as
* we support having MOVED_OFF/MOVED_IN tuples in the database.
*/
if (tuple->t_infomask & HEAP_MOVED)
{
xid = HeapTupleHeaderGetXvac(tuple);
/*
* For Xvac, we ignore the cutoff_xid and just always perform the
* freeze operation. The oldest release in which such a value can
* actually be set is PostgreSQL 8.4, because old-style VACUUM FULL
* was removed in PostgreSQL 9.0. Note that if we were to respect
* cutoff_xid here, we'd need to make surely to clear totally_frozen
* when we skipped freezing on that basis.
*/
if (TransactionIdIsNormal(xid))
{
/*
* If a MOVED_OFF tuple is not dead, the xvac transaction must
* have failed; whereas a non-dead MOVED_IN tuple must mean the
* xvac transaction succeeded.
*/
if (tuple->t_infomask & HEAP_MOVED_OFF)
frz->frzflags |= XLH_INVALID_XVAC;
else
frz->frzflags |= XLH_FREEZE_XVAC;
/*
* Might as well fix the hint bits too; usually XMIN_COMMITTED
* will already be set here, but there's a small chance not.
*/
Assert(!(tuple->t_infomask & HEAP_XMIN_INVALID));
frz->t_infomask |= HEAP_XMIN_COMMITTED;
changed = true;
}
}
*totally_frozen_p = (xmin_frozen &&
(freeze_xmax || xmax_already_frozen));
return changed;
}
/*
* heap_execute_freeze_tuple
* Execute the prepared freezing of a tuple.
*
* Caller is responsible for ensuring that no other backend can access the
* storage underlying this tuple, either by holding an exclusive lock on the
* buffer containing it (which is what lazy VACUUM does), or by having it be
* in private storage (which is what CLUSTER and friends do).
*
* Note: it might seem we could make the changes without exclusive lock, since
* TransactionId read/write is assumed atomic anyway. However there is a race
* condition: someone who just fetched an old XID that we overwrite here could
* conceivably not finish checking the XID against pg_xact before we finish
* the VACUUM and perhaps truncate off the part of pg_xact he needs. Getting
* exclusive lock ensures no other backend is in process of checking the
* tuple status. Also, getting exclusive lock makes it safe to adjust the
* infomask bits.
*
* NB: All code in here must be safe to execute during crash recovery!
*/
void
heap_execute_freeze_tuple(HeapTupleHeader tuple, xl_heap_freeze_tuple *frz)
{
HeapTupleHeaderSetXmax(tuple, frz->xmax);
if (frz->frzflags & XLH_FREEZE_XVAC)
HeapTupleHeaderSetXvac(tuple, FrozenTransactionId);
if (frz->frzflags & XLH_INVALID_XVAC)
HeapTupleHeaderSetXvac(tuple, InvalidTransactionId);
tuple->t_infomask = frz->t_infomask;
tuple->t_infomask2 = frz->t_infomask2;
}
/*
* heap_freeze_tuple
* Freeze tuple in place, without WAL logging.
*
* Useful for callers like CLUSTER that perform their own WAL logging.
*/
bool
heap_freeze_tuple(HeapTupleHeader tuple,
TransactionId relfrozenxid, TransactionId relminmxid,
TransactionId cutoff_xid, TransactionId cutoff_multi)
{
xl_heap_freeze_tuple frz;
bool do_freeze;
bool tuple_totally_frozen;
do_freeze = heap_prepare_freeze_tuple(tuple,
relfrozenxid, relminmxid,
cutoff_xid, cutoff_multi,
&frz, &tuple_totally_frozen);
/*
* Note that because this is not a WAL-logged operation, we don't need to
* fill in the offset in the freeze record.
*/
if (do_freeze)
heap_execute_freeze_tuple(tuple, &frz);
return do_freeze;
}
/*
* For a given MultiXactId, return the hint bits that should be set in the
* tuple's infomask.
*
* Normally this should be called for a multixact that was just created, and
* so is on our local cache, so the GetMembers call is fast.
*/
static void
GetMultiXactIdHintBits(MultiXactId multi, uint16 *new_infomask,
uint16 *new_infomask2)
{
int nmembers;
MultiXactMember *members;
int i;
uint16 bits = HEAP_XMAX_IS_MULTI;
uint16 bits2 = 0;
bool has_update = false;
LockTupleMode strongest = LockTupleKeyShare;
/*
* We only use this in multis we just created, so they cannot be values
* pre-pg_upgrade.
*/
nmembers = GetMultiXactIdMembers(multi, &members, false, false);
for (i = 0; i < nmembers; i++)
{
LockTupleMode mode;
/*
* Remember the strongest lock mode held by any member of the
* multixact.
*/
mode = TUPLOCK_from_mxstatus(members[i].status);
if (mode > strongest)
strongest = mode;
/* See what other bits we need */
switch (members[i].status)
{
case MultiXactStatusForKeyShare:
case MultiXactStatusForShare:
case MultiXactStatusForNoKeyUpdate:
break;
case MultiXactStatusForUpdate:
bits2 |= HEAP_KEYS_UPDATED;
break;
case MultiXactStatusNoKeyUpdate:
has_update = true;
break;
case MultiXactStatusUpdate:
bits2 |= HEAP_KEYS_UPDATED;
has_update = true;
break;
}
}
if (strongest == LockTupleExclusive ||
strongest == LockTupleNoKeyExclusive)
bits |= HEAP_XMAX_EXCL_LOCK;
else if (strongest == LockTupleShare)
bits |= HEAP_XMAX_SHR_LOCK;
else if (strongest == LockTupleKeyShare)
bits |= HEAP_XMAX_KEYSHR_LOCK;
if (!has_update)
bits |= HEAP_XMAX_LOCK_ONLY;
if (nmembers > 0)
pfree(members);
*new_infomask = bits;
*new_infomask2 = bits2;
}
/*
* MultiXactIdGetUpdateXid
*
* Given a multixact Xmax and corresponding infomask, which does not have the
* HEAP_XMAX_LOCK_ONLY bit set, obtain and return the Xid of the updating
* transaction.
*
* Caller is expected to check the status of the updating transaction, if
* necessary.
*/
static TransactionId
MultiXactIdGetUpdateXid(TransactionId xmax, uint16 t_infomask)
{
TransactionId update_xact = InvalidTransactionId;
MultiXactMember *members;
int nmembers;
Assert(!(t_infomask & HEAP_XMAX_LOCK_ONLY));
Assert(t_infomask & HEAP_XMAX_IS_MULTI);
/*
* Since we know the LOCK_ONLY bit is not set, this cannot be a multi from
* pre-pg_upgrade.
*/
nmembers = GetMultiXactIdMembers(xmax, &members, false, false);
if (nmembers > 0)
{
int i;
for (i = 0; i < nmembers; i++)
{
/* Ignore lockers */
if (!ISUPDATE_from_mxstatus(members[i].status))
continue;
/* there can be at most one updater */
Assert(update_xact == InvalidTransactionId);
update_xact = members[i].xid;
#ifndef USE_ASSERT_CHECKING
/*
* in an assert-enabled build, walk the whole array to ensure
* there's no other updater.
*/
break;
#endif
}
pfree(members);
}
return update_xact;
}
/*
* HeapTupleGetUpdateXid
* As above, but use a HeapTupleHeader
*
* See also HeapTupleHeaderGetUpdateXid, which can be used without previously
* checking the hint bits.
*/
TransactionId
HeapTupleGetUpdateXid(HeapTupleHeader tuple)
{
return MultiXactIdGetUpdateXid(HeapTupleHeaderGetRawXmax(tuple),
tuple->t_infomask);
}
/*
* Does the given multixact conflict with the current transaction grabbing a
* tuple lock of the given strength?
*
* The passed infomask pairs up with the given multixact in the tuple header.
*
* If current_is_member is not NULL, it is set to 'true' if the current
* transaction is a member of the given multixact.
*/
static bool
DoesMultiXactIdConflict(MultiXactId multi, uint16 infomask,
LockTupleMode lockmode, bool *current_is_member)
{
int nmembers;
MultiXactMember *members;
bool result = false;
LOCKMODE wanted = tupleLockExtraInfo[lockmode].hwlock;
if (HEAP_LOCKED_UPGRADED(infomask))
return false;
nmembers = GetMultiXactIdMembers(multi, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(infomask));
if (nmembers >= 0)
{
int i;
for (i = 0; i < nmembers; i++)
{
TransactionId memxid;
LOCKMODE memlockmode;
if (result && (current_is_member == NULL || *current_is_member))
break;
memlockmode = LOCKMODE_from_mxstatus(members[i].status);
/* ignore members from current xact (but track their presence) */
memxid = members[i].xid;
if (TransactionIdIsCurrentTransactionId(memxid))
{
if (current_is_member != NULL)
*current_is_member = true;
continue;
}
else if (result)
continue;
/* ignore members that don't conflict with the lock we want */
if (!DoLockModesConflict(memlockmode, wanted))
continue;
if (ISUPDATE_from_mxstatus(members[i].status))
{
/* ignore aborted updaters */
if (TransactionIdDidAbort(memxid))
continue;
}
else
{
/* ignore lockers-only that are no longer in progress */
if (!TransactionIdIsInProgress(memxid))
continue;
}
/*
* Whatever remains are either live lockers that conflict with our
* wanted lock, and updaters that are not aborted. Those conflict
* with what we want. Set up to return true, but keep going to
* look for the current transaction among the multixact members,
* if needed.
*/
result = true;
}
pfree(members);
}
return result;
}
/*
* Do_MultiXactIdWait
* Actual implementation for the two functions below.
*
* 'multi', 'status' and 'infomask' indicate what to sleep on (the status is
* needed to ensure we only sleep on conflicting members, and the infomask is
* used to optimize multixact access in case it's a lock-only multi); 'nowait'
* indicates whether to use conditional lock acquisition, to allow callers to
* fail if lock is unavailable. 'rel', 'ctid' and 'oper' are used to set up
* context information for error messages. 'remaining', if not NULL, receives
* the number of members that are still running, including any (non-aborted)
* subtransactions of our own transaction.
*
* We do this by sleeping on each member using XactLockTableWait. Any
* members that belong to the current backend are *not* waited for, however;
* this would not merely be useless but would lead to Assert failure inside
* XactLockTableWait. By the time this returns, it is certain that all
* transactions *of other backends* that were members of the MultiXactId
* that conflict with the requested status are dead (and no new ones can have
* been added, since it is not legal to add members to an existing
* MultiXactId).
*
* But by the time we finish sleeping, someone else may have changed the Xmax
* of the containing tuple, so the caller needs to iterate on us somehow.
*
* Note that in case we return false, the number of remaining members is
* not to be trusted.
*/
static bool
Do_MultiXactIdWait(MultiXactId multi, MultiXactStatus status,
uint16 infomask, bool nowait,
Relation rel, ItemPointer ctid, XLTW_Oper oper,
int *remaining)
{
bool result = true;
MultiXactMember *members;
int nmembers;
int remain = 0;
/* for pre-pg_upgrade tuples, no need to sleep at all */
nmembers = HEAP_LOCKED_UPGRADED(infomask) ? -1 :
GetMultiXactIdMembers(multi, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(infomask));
if (nmembers >= 0)
{
int i;
for (i = 0; i < nmembers; i++)
{
TransactionId memxid = members[i].xid;
MultiXactStatus memstatus = members[i].status;
if (TransactionIdIsCurrentTransactionId(memxid))
{
remain++;
continue;
}
if (!DoLockModesConflict(LOCKMODE_from_mxstatus(memstatus),
LOCKMODE_from_mxstatus(status)))
{
if (remaining && TransactionIdIsInProgress(memxid))
remain++;
continue;
}
/*
* This member conflicts with our multi, so we have to sleep (or
* return failure, if asked to avoid waiting.)
*
* Note that we don't set up an error context callback ourselves,
* but instead we pass the info down to XactLockTableWait. This
* might seem a bit wasteful because the context is set up and
* tore down for each member of the multixact, but in reality it
* should be barely noticeable, and it avoids duplicate code.
*/
if (nowait)
{
result = ConditionalXactLockTableWait(memxid);
if (!result)
break;
}
else
XactLockTableWait(memxid, rel, ctid, oper);
}
pfree(members);
}
if (remaining)
*remaining = remain;
return result;
}
/*
* MultiXactIdWait
* Sleep on a MultiXactId.
*
* By the time we finish sleeping, someone else may have changed the Xmax
* of the containing tuple, so the caller needs to iterate on us somehow.
*
* We return (in *remaining, if not NULL) the number of members that are still
* running, including any (non-aborted) subtransactions of our own transaction.
*/
static void
MultiXactIdWait(MultiXactId multi, MultiXactStatus status, uint16 infomask,
Relation rel, ItemPointer ctid, XLTW_Oper oper,
int *remaining)
{
(void) Do_MultiXactIdWait(multi, status, infomask, false,
rel, ctid, oper, remaining);
}
/*
* ConditionalMultiXactIdWait
* As above, but only lock if we can get the lock without blocking.
*
* By the time we finish sleeping, someone else may have changed the Xmax
* of the containing tuple, so the caller needs to iterate on us somehow.
*
* If the multixact is now all gone, return true. Returns false if some
* transactions might still be running.
*
* We return (in *remaining, if not NULL) the number of members that are still
* running, including any (non-aborted) subtransactions of our own transaction.
*/
static bool
ConditionalMultiXactIdWait(MultiXactId multi, MultiXactStatus status,
uint16 infomask, Relation rel, int *remaining)
{
return Do_MultiXactIdWait(multi, status, infomask, true,
rel, NULL, XLTW_None, remaining);
}
/*
* heap_tuple_needs_eventual_freeze
*
* Check to see whether any of the XID fields of a tuple (xmin, xmax, xvac)
* will eventually require freezing. Similar to heap_tuple_needs_freeze,
* but there's no cutoff, since we're trying to figure out whether freezing
* will ever be needed, not whether it's needed now.
*/
bool
heap_tuple_needs_eventual_freeze(HeapTupleHeader tuple)
{
TransactionId xid;
/*
* If xmin is a normal transaction ID, this tuple is definitely not
* frozen.
*/
xid = HeapTupleHeaderGetXmin(tuple);
if (TransactionIdIsNormal(xid))
return true;
/*
* If xmax is a valid xact or multixact, this tuple is also not frozen.
*/
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
{
MultiXactId multi;
multi = HeapTupleHeaderGetRawXmax(tuple);
if (MultiXactIdIsValid(multi))
return true;
}
else
{
xid = HeapTupleHeaderGetRawXmax(tuple);
if (TransactionIdIsNormal(xid))
return true;
}
if (tuple->t_infomask & HEAP_MOVED)
{
xid = HeapTupleHeaderGetXvac(tuple);
if (TransactionIdIsNormal(xid))
return true;
}
return false;
}
/*
* heap_tuple_needs_freeze
*
* Check to see whether any of the XID fields of a tuple (xmin, xmax, xvac)
* are older than the specified cutoff XID or MultiXactId. If so, return true.
*
* It doesn't matter whether the tuple is alive or dead, we are checking
* to see if a tuple needs to be removed or frozen to avoid wraparound.
*
* NB: Cannot rely on hint bits here, they might not be set after a crash or
* on a standby.
*/
bool
heap_tuple_needs_freeze(HeapTupleHeader tuple, TransactionId cutoff_xid,
MultiXactId cutoff_multi, Buffer buf)
{
TransactionId xid;
xid = HeapTupleHeaderGetXmin(tuple);
if (TransactionIdIsNormal(xid) &&
TransactionIdPrecedes(xid, cutoff_xid))
return true;
/*
* The considerations for multixacts are complicated; look at
* heap_prepare_freeze_tuple for justifications. This routine had better
* be in sync with that one!
*/
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
{
MultiXactId multi;
multi = HeapTupleHeaderGetRawXmax(tuple);
if (!MultiXactIdIsValid(multi))
{
/* no xmax set, ignore */
;
}
else if (HEAP_LOCKED_UPGRADED(tuple->t_infomask))
return true;
else if (MultiXactIdPrecedes(multi, cutoff_multi))
return true;
else
{
MultiXactMember *members;
int nmembers;
int i;
/* need to check whether any member of the mxact is too old */
nmembers = GetMultiXactIdMembers(multi, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask));
for (i = 0; i < nmembers; i++)
{
if (TransactionIdPrecedes(members[i].xid, cutoff_xid))
{
pfree(members);
return true;
}
}
if (nmembers > 0)
pfree(members);
}
}
else
{
xid = HeapTupleHeaderGetRawXmax(tuple);
if (TransactionIdIsNormal(xid) &&
TransactionIdPrecedes(xid, cutoff_xid))
return true;
}
if (tuple->t_infomask & HEAP_MOVED)
{
xid = HeapTupleHeaderGetXvac(tuple);
if (TransactionIdIsNormal(xid) &&
TransactionIdPrecedes(xid, cutoff_xid))
return true;
}
return false;
}
/*
* If 'tuple' contains any visible XID greater than latestRemovedXid,
* ratchet forwards latestRemovedXid to the greatest one found.
* This is used as the basis for generating Hot Standby conflicts, so
* if a tuple was never visible then removing it should not conflict
* with queries.
*/
void
HeapTupleHeaderAdvanceLatestRemovedXid(HeapTupleHeader tuple,
TransactionId *latestRemovedXid)
{
TransactionId xmin = HeapTupleHeaderGetXmin(tuple);
TransactionId xmax = HeapTupleHeaderGetUpdateXid(tuple);
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
if (tuple->t_infomask & HEAP_MOVED)
{
if (TransactionIdPrecedes(*latestRemovedXid, xvac))
*latestRemovedXid = xvac;
}
/*
* Ignore tuples inserted by an aborted transaction or if the tuple was
* updated/deleted by the inserting transaction.
*
* Look for a committed hint bit, or if no xmin bit is set, check clog.
* This needs to work on both master and standby, where it is used to
* assess btree delete records.
*/
if (HeapTupleHeaderXminCommitted(tuple) ||
(!HeapTupleHeaderXminInvalid(tuple) && TransactionIdDidCommit(xmin)))
{
if (xmax != xmin &&
TransactionIdFollows(xmax, *latestRemovedXid))
*latestRemovedXid = xmax;
}
/* *latestRemovedXid may still be invalid at end */
}
#ifdef USE_PREFETCH
/*
* Helper function for heap_compute_xid_horizon_for_tuples. Issue prefetch
* requests for the number of buffers indicated by prefetch_count. The
* prefetch_state keeps track of all the buffers that we can prefetch and
* which ones have already been prefetched; each call to this function picks
* up where the previous call left off.
*/
static void
xid_horizon_prefetch_buffer(Relation rel,
XidHorizonPrefetchState *prefetch_state,
int prefetch_count)
{
BlockNumber cur_hblkno = prefetch_state->cur_hblkno;
int count = 0;
int i;
int nitems = prefetch_state->nitems;
ItemPointerData *tids = prefetch_state->tids;
for (i = prefetch_state->next_item;
i < nitems && count < prefetch_count;
i++)
{
ItemPointer htid = &tids[i];
if (cur_hblkno == InvalidBlockNumber ||
ItemPointerGetBlockNumber(htid) != cur_hblkno)
{
cur_hblkno = ItemPointerGetBlockNumber(htid);
PrefetchBuffer(rel, MAIN_FORKNUM, cur_hblkno);
count++;
}
}
/*
* Save the prefetch position so that next time we can continue from that
* position.
*/
prefetch_state->next_item = i;
prefetch_state->cur_hblkno = cur_hblkno;
}
#endif
/*
* Get the latestRemovedXid from the heap pages pointed at by the index
* tuples being deleted.
*
* We used to do this during recovery rather than on the primary, but that
* approach now appears inferior. It meant that the master could generate
* a lot of work for the standby without any back-pressure to slow down the
* master, and it required the standby to have reached consistency, whereas
* we want to have correct information available even before that point.
*
* It's possible for this to generate a fair amount of I/O, since we may be
* deleting hundreds of tuples from a single index block. To amortize that
* cost to some degree, this uses prefetching and combines repeat accesses to
* the same block.
*/
TransactionId
heap_compute_xid_horizon_for_tuples(Relation rel,
ItemPointerData *tids,
int nitems)
{
TransactionId latestRemovedXid = InvalidTransactionId;
BlockNumber hblkno;
Buffer buf = InvalidBuffer;
Page hpage;
#ifdef USE_PREFETCH
XidHorizonPrefetchState prefetch_state;
int io_concurrency;
int prefetch_distance;
#endif
/*
* Sort to avoid repeated lookups for the same page, and to make it more
* likely to access items in an efficient order. In particular, this
* ensures that if there are multiple pointers to the same page, they all
* get processed looking up and locking the page just once.
*/
qsort((void *) tids, nitems, sizeof(ItemPointerData),
(int (*) (const void *, const void *)) ItemPointerCompare);
#ifdef USE_PREFETCH
/* Initialize prefetch state. */
prefetch_state.cur_hblkno = InvalidBlockNumber;
prefetch_state.next_item = 0;
prefetch_state.nitems = nitems;
prefetch_state.tids = tids;
/*
* Compute the prefetch distance that we will attempt to maintain.
*
* We don't use the regular formula to determine how much to prefetch
* here, but instead just add a constant to effective_io_concurrency.
* That's because it seems best to do some prefetching here even when
* effective_io_concurrency is set to 0, but if the DBA thinks it's OK to
* do more prefetching for other operations, then it's probably OK to do
* more prefetching in this case, too. It may be that this formula is too
* simplistic, but at the moment there is no evidence of that or any idea
* about what would work better.
*
* Since the caller holds a buffer lock somewhere in rel, we'd better make
* sure that isn't a catalog relation before we call code that does
* syscache lookups, to avoid risk of deadlock.
*/
if (IsCatalogRelation(rel))
io_concurrency = effective_io_concurrency;
else
io_concurrency = get_tablespace_io_concurrency(rel->rd_rel->reltablespace);
prefetch_distance = Min((io_concurrency) + 10, MAX_IO_CONCURRENCY);
/* Start prefetching. */
xid_horizon_prefetch_buffer(rel, &prefetch_state, prefetch_distance);
#endif
/* Iterate over all tids, and check their horizon */
hblkno = InvalidBlockNumber;
hpage = NULL;
for (int i = 0; i < nitems; i++)
{
ItemPointer htid = &tids[i];
ItemId hitemid;
OffsetNumber hoffnum;
/*
* Read heap buffer, but avoid refetching if it's the same block as
* required for the last tid.
*/
if (hblkno == InvalidBlockNumber ||
ItemPointerGetBlockNumber(htid) != hblkno)
{
/* release old buffer */
if (BufferIsValid(buf))
{
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buf);
}
hblkno = ItemPointerGetBlockNumber(htid);
buf = ReadBuffer(rel, hblkno);
#ifdef USE_PREFETCH
/*
* To maintain the prefetch distance, prefetch one more page for
* each page we read.
*/
xid_horizon_prefetch_buffer(rel, &prefetch_state, 1);
#endif
hpage = BufferGetPage(buf);
LockBuffer(buf, BUFFER_LOCK_SHARE);
}
hoffnum = ItemPointerGetOffsetNumber(htid);
hitemid = PageGetItemId(hpage, hoffnum);
/*
* Follow any redirections until we find something useful.
*/
while (ItemIdIsRedirected(hitemid))
{
hoffnum = ItemIdGetRedirect(hitemid);
hitemid = PageGetItemId(hpage, hoffnum);
CHECK_FOR_INTERRUPTS();
}
/*
* If the heap item has storage, then read the header and use that to
* set latestRemovedXid.
*
* Some LP_DEAD items may not be accessible, so we ignore them.
*/
if (ItemIdHasStorage(hitemid))
{
HeapTupleHeader htuphdr;
htuphdr = (HeapTupleHeader) PageGetItem(hpage, hitemid);
HeapTupleHeaderAdvanceLatestRemovedXid(htuphdr, &latestRemovedXid);
}
else if (ItemIdIsDead(hitemid))
{
/*
* Conjecture: if hitemid is dead then it had xids before the xids
* marked on LP_NORMAL items. So we just ignore this item and move
* onto the next, for the purposes of calculating
* latestRemovedXid.
*/
}
else
Assert(!ItemIdIsUsed(hitemid));
}
if (BufferIsValid(buf))
{
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buf);
}
/*
* If all heap tuples were LP_DEAD then we will be returning
* InvalidTransactionId here, which avoids conflicts. This matches
* existing logic which assumes that LP_DEAD tuples must already be older
* than the latestRemovedXid on the cleanup record that set them as
* LP_DEAD, hence must already have generated a conflict.
*/
return latestRemovedXid;
}
/*
* Perform XLogInsert to register a heap cleanup info message. These
* messages are sent once per VACUUM and are required because
* of the phasing of removal operations during a lazy VACUUM.
* see comments for vacuum_log_cleanup_info().
*/
XLogRecPtr
log_heap_cleanup_info(RelFileNode rnode, TransactionId latestRemovedXid)
{
xl_heap_cleanup_info xlrec;
XLogRecPtr recptr;
xlrec.node = rnode;
xlrec.latestRemovedXid = latestRemovedXid;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapCleanupInfo);
recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_CLEANUP_INFO);
return recptr;
}
/*
* Perform XLogInsert for a heap-clean operation. Caller must already
* have modified the buffer and marked it dirty.
*
* Note: prior to Postgres 8.3, the entries in the nowunused[] array were
* zero-based tuple indexes. Now they are one-based like other uses
* of OffsetNumber.
*
* We also include latestRemovedXid, which is the greatest XID present in
* the removed tuples. That allows recovery processing to cancel or wait
* for long standby queries that can still see these tuples.
*/
XLogRecPtr
log_heap_clean(Relation reln, Buffer buffer,
OffsetNumber *redirected, int nredirected,
OffsetNumber *nowdead, int ndead,
OffsetNumber *nowunused, int nunused,
TransactionId latestRemovedXid)
{
xl_heap_clean xlrec;
XLogRecPtr recptr;
/* Caller should not call me on a non-WAL-logged relation */
Assert(RelationNeedsWAL(reln));
xlrec.latestRemovedXid = latestRemovedXid;
xlrec.nredirected = nredirected;
xlrec.ndead = ndead;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapClean);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
/*
* The OffsetNumber arrays are not actually in the buffer, but we pretend
* that they are. When XLogInsert stores the whole buffer, the offset
* arrays need not be stored too. Note that even if all three arrays are
* empty, we want to expose the buffer as a candidate for whole-page
* storage, since this record type implies a defragmentation operation
* even if no line pointers changed state.
*/
if (nredirected > 0)
XLogRegisterBufData(0, (char *) redirected,
nredirected * sizeof(OffsetNumber) * 2);
if (ndead > 0)
XLogRegisterBufData(0, (char *) nowdead,
ndead * sizeof(OffsetNumber));
if (nunused > 0)
XLogRegisterBufData(0, (char *) nowunused,
nunused * sizeof(OffsetNumber));
recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_CLEAN);
return recptr;
}
/*
* Perform XLogInsert for a heap-freeze operation. Caller must have already
* modified the buffer and marked it dirty.
*/
XLogRecPtr
log_heap_freeze(Relation reln, Buffer buffer, TransactionId cutoff_xid,
xl_heap_freeze_tuple *tuples, int ntuples)
{
xl_heap_freeze_page xlrec;
XLogRecPtr recptr;
/* Caller should not call me on a non-WAL-logged relation */
Assert(RelationNeedsWAL(reln));
/* nor when there are no tuples to freeze */
Assert(ntuples > 0);
xlrec.cutoff_xid = cutoff_xid;
xlrec.ntuples = ntuples;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
/*
* The freeze plan array is not actually in the buffer, but pretend that
* it is. When XLogInsert stores the whole buffer, the freeze plan need
* not be stored too.
*/
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
XLogRegisterBufData(0, (char *) tuples,
ntuples * sizeof(xl_heap_freeze_tuple));
recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
return recptr;
}
/*
* Perform XLogInsert for a heap-visible operation. 'block' is the block
* being marked all-visible, and vm_buffer is the buffer containing the
* corresponding visibility map block. Both should have already been modified
* and dirtied.
*
* If checksums are enabled, we also generate a full-page image of
* heap_buffer, if necessary.
*/
XLogRecPtr
log_heap_visible(RelFileNode rnode, Buffer heap_buffer, Buffer vm_buffer,
TransactionId cutoff_xid, uint8 vmflags)
{
xl_heap_visible xlrec;
XLogRecPtr recptr;
uint8 flags;
Assert(BufferIsValid(heap_buffer));
Assert(BufferIsValid(vm_buffer));
xlrec.cutoff_xid = cutoff_xid;
xlrec.flags = vmflags;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapVisible);
XLogRegisterBuffer(0, vm_buffer, 0);
flags = REGBUF_STANDARD;
if (!XLogHintBitIsNeeded())
flags |= REGBUF_NO_IMAGE;
XLogRegisterBuffer(1, heap_buffer, flags);
recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_VISIBLE);
return recptr;
}
/*
* Perform XLogInsert for a heap-update operation. Caller must already
* have modified the buffer(s) and marked them dirty.
*/
static XLogRecPtr
log_heap_update(Relation reln, Buffer oldbuf,
Buffer newbuf, HeapTuple oldtup, HeapTuple newtup,
HeapTuple old_key_tuple,
bool all_visible_cleared, bool new_all_visible_cleared)
{
xl_heap_update xlrec;
xl_heap_header xlhdr;
xl_heap_header xlhdr_idx;
uint8 info;
uint16 prefix_suffix[2];
uint16 prefixlen = 0,
suffixlen = 0;
XLogRecPtr recptr;
Page page = BufferGetPage(newbuf);
bool need_tuple_data = RelationIsLogicallyLogged(reln);
bool init;
int bufflags;
/* Caller should not call me on a non-WAL-logged relation */
Assert(RelationNeedsWAL(reln));
XLogBeginInsert();
if (HeapTupleIsHeapOnly(newtup))
info = XLOG_HEAP_HOT_UPDATE;
else
info = XLOG_HEAP_UPDATE;
/*
* If the old and new tuple are on the same page, we only need to log the
* parts of the new tuple that were changed. That saves on the amount of
* WAL we need to write. Currently, we just count any unchanged bytes in
* the beginning and end of the tuple. That's quick to check, and
* perfectly covers the common case that only one field is updated.
*
* We could do this even if the old and new tuple are on different pages,
* but only if we don't make a full-page image of the old page, which is
* difficult to know in advance. Also, if the old tuple is corrupt for
* some reason, it would allow the corruption to propagate the new page,
* so it seems best to avoid. Under the general assumption that most
* updates tend to create the new tuple version on the same page, there
* isn't much to be gained by doing this across pages anyway.
*
* Skip this if we're taking a full-page image of the new page, as we
* don't include the new tuple in the WAL record in that case. Also
* disable if wal_level='logical', as logical decoding needs to be able to
* read the new tuple in whole from the WAL record alone.
*/
if (oldbuf == newbuf && !need_tuple_data &&
!XLogCheckBufferNeedsBackup(newbuf))
{
char *oldp = (char *) oldtup->t_data + oldtup->t_data->t_hoff;
char *newp = (char *) newtup->t_data + newtup->t_data->t_hoff;
int oldlen = oldtup->t_len - oldtup->t_data->t_hoff;
int newlen = newtup->t_len - newtup->t_data->t_hoff;
/* Check for common prefix between old and new tuple */
for (prefixlen = 0; prefixlen < Min(oldlen, newlen); prefixlen++)
{
if (newp[prefixlen] != oldp[prefixlen])
break;
}
/*
* Storing the length of the prefix takes 2 bytes, so we need to save
* at least 3 bytes or there's no point.
*/
if (prefixlen < 3)
prefixlen = 0;
/* Same for suffix */
for (suffixlen = 0; suffixlen < Min(oldlen, newlen) - prefixlen; suffixlen++)
{
if (newp[newlen - suffixlen - 1] != oldp[oldlen - suffixlen - 1])
break;
}
if (suffixlen < 3)
suffixlen = 0;
}
/* Prepare main WAL data chain */
xlrec.flags = 0;
if (all_visible_cleared)
xlrec.flags |= XLH_UPDATE_OLD_ALL_VISIBLE_CLEARED;
if (new_all_visible_cleared)
xlrec.flags |= XLH_UPDATE_NEW_ALL_VISIBLE_CLEARED;
if (prefixlen > 0)
xlrec.flags |= XLH_UPDATE_PREFIX_FROM_OLD;
if (suffixlen > 0)
xlrec.flags |= XLH_UPDATE_SUFFIX_FROM_OLD;
if (need_tuple_data)
{
xlrec.flags |= XLH_UPDATE_CONTAINS_NEW_TUPLE;
if (old_key_tuple)
{
if (reln->rd_rel->relreplident == REPLICA_IDENTITY_FULL)
xlrec.flags |= XLH_UPDATE_CONTAINS_OLD_TUPLE;
else
xlrec.flags |= XLH_UPDATE_CONTAINS_OLD_KEY;
}
}
/* If new tuple is the single and first tuple on page... */
if (ItemPointerGetOffsetNumber(&(newtup->t_self)) == FirstOffsetNumber &&
PageGetMaxOffsetNumber(page) == FirstOffsetNumber)
{
info |= XLOG_HEAP_INIT_PAGE;
init = true;
}
else
init = false;
/* Prepare WAL data for the old page */
xlrec.old_offnum = ItemPointerGetOffsetNumber(&oldtup->t_self);
xlrec.old_xmax = HeapTupleHeaderGetRawXmax(oldtup->t_data);
xlrec.old_infobits_set = compute_infobits(oldtup->t_data->t_infomask,
oldtup->t_data->t_infomask2);
/* Prepare WAL data for the new page */
xlrec.new_offnum = ItemPointerGetOffsetNumber(&newtup->t_self);
xlrec.new_xmax = HeapTupleHeaderGetRawXmax(newtup->t_data);
bufflags = REGBUF_STANDARD;
if (init)
bufflags |= REGBUF_WILL_INIT;
if (need_tuple_data)
bufflags |= REGBUF_KEEP_DATA;
XLogRegisterBuffer(0, newbuf, bufflags);
if (oldbuf != newbuf)
XLogRegisterBuffer(1, oldbuf, REGBUF_STANDARD);
XLogRegisterData((char *) &xlrec, SizeOfHeapUpdate);
/*
* Prepare WAL data for the new tuple.
*/
if (prefixlen > 0 || suffixlen > 0)
{
if (prefixlen > 0 && suffixlen > 0)
{
prefix_suffix[0] = prefixlen;
prefix_suffix[1] = suffixlen;
XLogRegisterBufData(0, (char *) &prefix_suffix, sizeof(uint16) * 2);
}
else if (prefixlen > 0)
{
XLogRegisterBufData(0, (char *) &prefixlen, sizeof(uint16));
}
else
{
XLogRegisterBufData(0, (char *) &suffixlen, sizeof(uint16));
}
}
xlhdr.t_infomask2 = newtup->t_data->t_infomask2;
xlhdr.t_infomask = newtup->t_data->t_infomask;
xlhdr.t_hoff = newtup->t_data->t_hoff;
Assert(SizeofHeapTupleHeader + prefixlen + suffixlen <= newtup->t_len);
/*
* PG73FORMAT: write bitmap [+ padding] [+ oid] + data
*
* The 'data' doesn't include the common prefix or suffix.
*/
XLogRegisterBufData(0, (char *) &xlhdr, SizeOfHeapHeader);
if (prefixlen == 0)
{
XLogRegisterBufData(0,
((char *) newtup->t_data) + SizeofHeapTupleHeader,
newtup->t_len - SizeofHeapTupleHeader - suffixlen);
}
else
{
/*
* Have to write the null bitmap and data after the common prefix as
* two separate rdata entries.
*/
/* bitmap [+ padding] [+ oid] */
if (newtup->t_data->t_hoff - SizeofHeapTupleHeader > 0)
{
XLogRegisterBufData(0,
((char *) newtup->t_data) + SizeofHeapTupleHeader,
newtup->t_data->t_hoff - SizeofHeapTupleHeader);
}
/* data after common prefix */
XLogRegisterBufData(0,
((char *) newtup->t_data) + newtup->t_data->t_hoff + prefixlen,
newtup->t_len - newtup->t_data->t_hoff - prefixlen - suffixlen);
}
/* We need to log a tuple identity */
if (need_tuple_data && old_key_tuple)
{
/* don't really need this, but its more comfy to decode */
xlhdr_idx.t_infomask2 = old_key_tuple->t_data->t_infomask2;
xlhdr_idx.t_infomask = old_key_tuple->t_data->t_infomask;
xlhdr_idx.t_hoff = old_key_tuple->t_data->t_hoff;
XLogRegisterData((char *) &xlhdr_idx, SizeOfHeapHeader);
/* PG73FORMAT: write bitmap [+ padding] [+ oid] + data */
XLogRegisterData((char *) old_key_tuple->t_data + SizeofHeapTupleHeader,
old_key_tuple->t_len - SizeofHeapTupleHeader);
}
/* filtering by origin on a row level is much more efficient */
XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN);
recptr = XLogInsert(RM_HEAP_ID, info);
return recptr;
}
/*
* Perform XLogInsert of an XLOG_HEAP2_NEW_CID record
*
* This is only used in wal_level >= WAL_LEVEL_LOGICAL, and only for catalog
* tuples.
*/
static XLogRecPtr
log_heap_new_cid(Relation relation, HeapTuple tup)
{
xl_heap_new_cid xlrec;
XLogRecPtr recptr;
HeapTupleHeader hdr = tup->t_data;
Assert(ItemPointerIsValid(&tup->t_self));
Assert(tup->t_tableOid != InvalidOid);
xlrec.top_xid = GetTopTransactionId();
xlrec.target_node = relation->rd_node;
xlrec.target_tid = tup->t_self;
/*
* If the tuple got inserted & deleted in the same TX we definitely have a
* combocid, set cmin and cmax.
*/
if (hdr->t_infomask & HEAP_COMBOCID)
{
Assert(!(hdr->t_infomask & HEAP_XMAX_INVALID));
Assert(!HeapTupleHeaderXminInvalid(hdr));
xlrec.cmin = HeapTupleHeaderGetCmin(hdr);
xlrec.cmax = HeapTupleHeaderGetCmax(hdr);
xlrec.combocid = HeapTupleHeaderGetRawCommandId(hdr);
}
/* No combocid, so only cmin or cmax can be set by this TX */
else
{
/*
* Tuple inserted.
*
* We need to check for LOCK ONLY because multixacts might be
* transferred to the new tuple in case of FOR KEY SHARE updates in
* which case there will be an xmax, although the tuple just got
* inserted.
*/
if (hdr->t_infomask & HEAP_XMAX_INVALID ||
HEAP_XMAX_IS_LOCKED_ONLY(hdr->t_infomask))
{
xlrec.cmin = HeapTupleHeaderGetRawCommandId(hdr);
xlrec.cmax = InvalidCommandId;
}
/* Tuple from a different tx updated or deleted. */
else
{
xlrec.cmin = InvalidCommandId;
xlrec.cmax = HeapTupleHeaderGetRawCommandId(hdr);
}
xlrec.combocid = InvalidCommandId;
}
/*
* Note that we don't need to register the buffer here, because this
* operation does not modify the page. The insert/update/delete that
* called us certainly did, but that's WAL-logged separately.
*/
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapNewCid);
/* will be looked at irrespective of origin */
recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_NEW_CID);
return recptr;
}
/*
* Build a heap tuple representing the configured REPLICA IDENTITY to represent
* the old tuple in a UPDATE or DELETE.
*
* Returns NULL if there's no need to log an identity or if there's no suitable
* key in the Relation relation.
*/
static HeapTuple
ExtractReplicaIdentity(Relation relation, HeapTuple tp, bool key_changed, bool *copy)
{
TupleDesc desc = RelationGetDescr(relation);
Oid replidindex;
Relation idx_rel;
char replident = relation->rd_rel->relreplident;
HeapTuple key_tuple = NULL;
bool nulls[MaxHeapAttributeNumber];
Datum values[MaxHeapAttributeNumber];
int natt;
*copy = false;
if (!RelationIsLogicallyLogged(relation))
return NULL;
if (replident == REPLICA_IDENTITY_NOTHING)
return NULL;
if (replident == REPLICA_IDENTITY_FULL)
{
/*
* When logging the entire old tuple, it very well could contain
* toasted columns. If so, force them to be inlined.
*/
if (HeapTupleHasExternal(tp))
{
*copy = true;
tp = toast_flatten_tuple(tp, RelationGetDescr(relation));
}
return tp;
}
/* if the key hasn't changed and we're only logging the key, we're done */
if (!key_changed)
return NULL;
/* find the replica identity index */
replidindex = RelationGetReplicaIndex(relation);
if (!OidIsValid(replidindex))
{
elog(DEBUG4, "could not find configured replica identity for table \"%s\"",
RelationGetRelationName(relation));
return NULL;
}
idx_rel = RelationIdGetRelation(replidindex);
Assert(CheckRelationLockedByMe(idx_rel, AccessShareLock, true));
/* deform tuple, so we have fast access to columns */
heap_deform_tuple(tp, desc, values, nulls);
/* set all columns to NULL, regardless of whether they actually are */
memset(nulls, 1, sizeof(nulls));
/*
* Now set all columns contained in the index to NOT NULL, they cannot
* currently be NULL.
*/
for (natt = 0; natt < IndexRelationGetNumberOfKeyAttributes(idx_rel); natt++)
{
int attno = idx_rel->rd_index->indkey.values[natt];
if (attno < 0)
elog(ERROR, "system column in index");
nulls[attno - 1] = false;
}
key_tuple = heap_form_tuple(desc, values, nulls);
*copy = true;
RelationClose(idx_rel);
/*
* If the tuple, which by here only contains indexed columns, still has
* toasted columns, force them to be inlined. This is somewhat unlikely
* since there's limits on the size of indexed columns, so we don't
* duplicate toast_flatten_tuple()s functionality in the above loop over
* the indexed columns, even if it would be more efficient.
*/
if (HeapTupleHasExternal(key_tuple))
{
HeapTuple oldtup = key_tuple;
key_tuple = toast_flatten_tuple(oldtup, RelationGetDescr(relation));
heap_freetuple(oldtup);
}
return key_tuple;
}
/*
* Handles CLEANUP_INFO
*/
static void
heap_xlog_cleanup_info(XLogReaderState *record)
{
xl_heap_cleanup_info *xlrec = (xl_heap_cleanup_info *) XLogRecGetData(record);
if (InHotStandby)
ResolveRecoveryConflictWithSnapshot(xlrec->latestRemovedXid, xlrec->node);
/*
* Actual operation is a no-op. Record type exists to provide a means for
* conflict processing to occur before we begin index vacuum actions. see
* vacuumlazy.c and also comments in btvacuumpage()
*/
/* Backup blocks are not used in cleanup_info records */
Assert(!XLogRecHasAnyBlockRefs(record));
}
/*
* Handles XLOG_HEAP2_CLEAN record type
*/
static void
heap_xlog_clean(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_clean *xlrec = (xl_heap_clean *) XLogRecGetData(record);
Buffer buffer;
RelFileNode rnode;
BlockNumber blkno;
XLogRedoAction action;
XLogRecGetBlockTag(record, 0, &rnode, NULL, &blkno);
/*
* We're about to remove tuples. In Hot Standby mode, ensure that there's
* no queries running for which the removed tuples are still visible.
*
* Not all HEAP2_CLEAN records remove tuples with xids, so we only want to
* conflict on the records that cause MVCC failures for user queries. If
* latestRemovedXid is invalid, skip conflict processing.
*/
if (InHotStandby && TransactionIdIsValid(xlrec->latestRemovedXid))
ResolveRecoveryConflictWithSnapshot(xlrec->latestRemovedXid, rnode);
/*
* If we have a full-page image, restore it (using a cleanup lock) and
* we're done.
*/
action = XLogReadBufferForRedoExtended(record, 0, RBM_NORMAL, true,
&buffer);
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
Size datalen;
redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
end = (OffsetNumber *) ((char *) redirected + datalen);
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
nunused = (end - nowunused);
Assert(nunused >= 0);
/* Update all line pointers per the record, and repair fragmentation */
heap_page_prune_execute(buffer,
redirected, nredirected,
nowdead, ndead,
nowunused, nunused);
/*
* Note: we don't worry about updating the page's prunability hints.
* At worst this will cause an extra prune cycle to occur soon.
*/
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
{
Size freespace = PageGetHeapFreeSpace(BufferGetPage(buffer));
UnlockReleaseBuffer(buffer);
/*
* After cleaning records from a page, it's useful to update the FSM
* about it, as it may cause the page become target for insertions
* later even if vacuum decides not to visit it (which is possible if
* gets marked all-visible.)
*
* Do this regardless of a full-page image being applied, since the
* FSM data is not in the page anyway.
*/
XLogRecordPageWithFreeSpace(rnode, blkno, freespace);
}
}
/*
* Replay XLOG_HEAP2_VISIBLE record.
*
* The critical integrity requirement here is that we must never end up with
* a situation where the visibility map bit is set, and the page-level
* PD_ALL_VISIBLE bit is clear. If that were to occur, then a subsequent
* page modification would fail to clear the visibility map bit.
*/
static void
heap_xlog_visible(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_visible *xlrec = (xl_heap_visible *) XLogRecGetData(record);
Buffer vmbuffer = InvalidBuffer;
Buffer buffer;
Page page;
RelFileNode rnode;
BlockNumber blkno;
XLogRedoAction action;
XLogRecGetBlockTag(record, 1, &rnode, NULL, &blkno);
/*
* If there are any Hot Standby transactions running that have an xmin
* horizon old enough that this page isn't all-visible for them, they
* might incorrectly decide that an index-only scan can skip a heap fetch.
*
* NB: It might be better to throw some kind of "soft" conflict here that
* forces any index-only scan that is in flight to perform heap fetches,
* rather than killing the transaction outright.
*/
if (InHotStandby)
ResolveRecoveryConflictWithSnapshot(xlrec->cutoff_xid, rnode);
/*
* Read the heap page, if it still exists. If the heap file has dropped or
* truncated later in recovery, we don't need to update the page, but we'd
* better still update the visibility map.
*/
action = XLogReadBufferForRedo(record, 1, &buffer);
if (action == BLK_NEEDS_REDO)
{
/*
* We don't bump the LSN of the heap page when setting the visibility
* map bit (unless checksums or wal_hint_bits is enabled, in which
* case we must), because that would generate an unworkable volume of
* full-page writes. This exposes us to torn page hazards, but since
* we're not inspecting the existing page contents in any way, we
* don't care.
*
* However, all operations that clear the visibility map bit *do* bump
* the LSN, and those operations will only be replayed if the XLOG LSN
* follows the page LSN. Thus, if the page LSN has advanced past our
* XLOG record's LSN, we mustn't mark the page all-visible, because
* the subsequent update won't be replayed to clear the flag.
*/
page = BufferGetPage(buffer);
PageSetAllVisible(page);
MarkBufferDirty(buffer);
}
else if (action == BLK_RESTORED)
{
/*
* If heap block was backed up, we already restored it and there's
* nothing more to do. (This can only happen with checksums or
* wal_log_hints enabled.)
*/
}
if (BufferIsValid(buffer))
{
Size space = PageGetFreeSpace(BufferGetPage(buffer));
UnlockReleaseBuffer(buffer);
/*
* Since FSM is not WAL-logged and only updated heuristically, it
* easily becomes stale in standbys. If the standby is later promoted
* and runs VACUUM, it will skip updating individual free space
* figures for pages that became all-visible (or all-frozen, depending
* on the vacuum mode,) which is troublesome when FreeSpaceMapVacuum
* propagates too optimistic free space values to upper FSM layers;
* later inserters try to use such pages only to find out that they
* are unusable. This can cause long stalls when there are many such
* pages.
*
* Forestall those problems by updating FSM's idea about a page that
* is becoming all-visible or all-frozen.
*
* Do this regardless of a full-page image being applied, since the
* FSM data is not in the page anyway.
*/
if (xlrec->flags & VISIBILITYMAP_VALID_BITS)
XLogRecordPageWithFreeSpace(rnode, blkno, space);
}
/*
* Even if we skipped the heap page update due to the LSN interlock, it's
* still safe to update the visibility map. Any WAL record that clears
* the visibility map bit does so before checking the page LSN, so any
* bits that need to be cleared will still be cleared.
*/
if (XLogReadBufferForRedoExtended(record, 0, RBM_ZERO_ON_ERROR, false,
&vmbuffer) == BLK_NEEDS_REDO)
{
Page vmpage = BufferGetPage(vmbuffer);
Relation reln;
/* initialize the page if it was read as zeros */
if (PageIsNew(vmpage))
PageInit(vmpage, BLCKSZ, 0);
/*
* XLogReadBufferForRedoExtended locked the buffer. But
* visibilitymap_set will handle locking itself.
*/
LockBuffer(vmbuffer, BUFFER_LOCK_UNLOCK);
reln = CreateFakeRelcacheEntry(rnode);
visibilitymap_pin(reln, blkno, &vmbuffer);
/*
* Don't set the bit if replay has already passed this point.
*
* It might be safe to do this unconditionally; if replay has passed
* this point, we'll replay at least as far this time as we did
* before, and if this bit needs to be cleared, the record responsible
* for doing so should be again replayed, and clear it. For right
* now, out of an abundance of conservatism, we use the same test here
* we did for the heap page. If this results in a dropped bit, no
* real harm is done; and the next VACUUM will fix it.
*/
/*
* CDB: don't use PageGetLSN here, GPDB PageGetLSN checks the buffer
* is locked. But here vmbuffer is in function visibilitymap_set().
*
* if (lsn > PageGetLSN(vmpage))
* visibilitymap_set(reln, blkno, InvalidBuffer, lsn, vmbuffer,
* xlrec->cutoff_xid);
*/
if (lsn > PageXLogRecPtrGet(((PageHeader) vmpage)->pd_lsn))
visibilitymap_set(reln, blkno, InvalidBuffer, lsn, vmbuffer,
xlrec->cutoff_xid, xlrec->flags);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
else if (BufferIsValid(vmbuffer))
UnlockReleaseBuffer(vmbuffer);
}
/*
* Replay XLOG_HEAP2_FREEZE_PAGE records
*/
static void
heap_xlog_freeze_page(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_freeze_page *xlrec = (xl_heap_freeze_page *) XLogRecGetData(record);
TransactionId cutoff_xid = xlrec->cutoff_xid;
Buffer buffer;
int ntup;
/*
* In Hot Standby mode, ensure that there's no queries running which still
* consider the frozen xids as running.
*/
if (InHotStandby)
{
RelFileNode rnode;
TransactionId latestRemovedXid = cutoff_xid;
TransactionIdRetreat(latestRemovedXid);
XLogRecGetBlockTag(record, 0, &rnode, NULL, NULL);
ResolveRecoveryConflictWithSnapshot(latestRemovedXid, rnode);
}
if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
{
Page page = BufferGetPage(buffer);
xl_heap_freeze_tuple *tuples;
tuples = (xl_heap_freeze_tuple *) XLogRecGetBlockData(record, 0, NULL);
/* now execute freeze plan for each frozen tuple */
for (ntup = 0; ntup < xlrec->ntuples; ntup++)
{
xl_heap_freeze_tuple *xlrec_tp;
ItemId lp;
HeapTupleHeader tuple;
xlrec_tp = &tuples[ntup];
lp = PageGetItemId(page, xlrec_tp->offset); /* offsets are one-based */
tuple = (HeapTupleHeader) PageGetItem(page, lp);
heap_execute_freeze_tuple(tuple, xlrec_tp);
}
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
}
/*
* Given an "infobits" field from an XLog record, set the correct bits in the
* given infomask and infomask2 for the tuple touched by the record.
*
* (This is the reverse of compute_infobits).
*/
static void
fix_infomask_from_infobits(uint8 infobits, uint16 *infomask, uint16 *infomask2)
{
*infomask &= ~(HEAP_XMAX_IS_MULTI | HEAP_XMAX_LOCK_ONLY |
HEAP_XMAX_KEYSHR_LOCK | HEAP_XMAX_EXCL_LOCK);
*infomask2 &= ~HEAP_KEYS_UPDATED;
if (infobits & XLHL_XMAX_IS_MULTI)
*infomask |= HEAP_XMAX_IS_MULTI;
if (infobits & XLHL_XMAX_LOCK_ONLY)
*infomask |= HEAP_XMAX_LOCK_ONLY;
if (infobits & XLHL_XMAX_EXCL_LOCK)
*infomask |= HEAP_XMAX_EXCL_LOCK;
/* note HEAP_XMAX_SHR_LOCK isn't considered here */
if (infobits & XLHL_XMAX_KEYSHR_LOCK)
*infomask |= HEAP_XMAX_KEYSHR_LOCK;
if (infobits & XLHL_KEYS_UPDATED)
*infomask2 |= HEAP_KEYS_UPDATED;
}
static void
heap_xlog_delete(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_delete *xlrec = (xl_heap_delete *) XLogRecGetData(record);
Buffer buffer;
Page page;
ItemId lp = NULL;
HeapTupleHeader htup;
BlockNumber blkno;
RelFileNode target_node;
ItemPointerData target_tid;
XLogRecGetBlockTag(record, 0, &target_node, NULL, &blkno);
ItemPointerSetBlockNumber(&target_tid, blkno);
ItemPointerSetOffsetNumber(&target_tid, xlrec->offnum);
/*
* The visibility map may need to be fixed even if the heap page is
* already up-to-date.
*/
if (xlrec->flags & XLH_DELETE_ALL_VISIBLE_CLEARED)
{
Relation reln = CreateFakeRelcacheEntry(target_node);
Buffer vmbuffer = InvalidBuffer;
visibilitymap_pin(reln, blkno, &vmbuffer);
visibilitymap_clear(reln, blkno, vmbuffer, VISIBILITYMAP_VALID_BITS);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
{
page = BufferGetPage(buffer);
if (PageGetMaxOffsetNumber(page) >= xlrec->offnum)
lp = PageGetItemId(page, xlrec->offnum);
if (PageGetMaxOffsetNumber(page) < xlrec->offnum || !ItemIdIsNormal(lp))
elog(PANIC, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
htup->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
htup->t_infomask2 &= ~HEAP_KEYS_UPDATED;
HeapTupleHeaderClearHotUpdated(htup);
fix_infomask_from_infobits(xlrec->infobits_set,
&htup->t_infomask, &htup->t_infomask2);
if (!(xlrec->flags & XLH_DELETE_IS_SUPER))
HeapTupleHeaderSetXmax(htup, xlrec->xmax);
else
HeapTupleHeaderSetXmin(htup, InvalidTransactionId);
HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
/* Mark the page as a candidate for pruning */
PageSetPrunable(page, XLogRecGetXid(record));
if (xlrec->flags & XLH_DELETE_ALL_VISIBLE_CLEARED)
PageClearAllVisible(page);
/* Make sure t_ctid is set correctly */
if (xlrec->flags & XLH_DELETE_IS_PARTITION_MOVE)
HeapTupleHeaderSetMovedPartitions(htup);
else
htup->t_ctid = target_tid;
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
}
static void
heap_xlog_insert(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_insert *xlrec = (xl_heap_insert *) XLogRecGetData(record);
Buffer buffer;
Page page;
union
{
HeapTupleHeaderData hdr;
char data[MaxHeapTupleSize];
} tbuf;
HeapTupleHeader htup;
xl_heap_header xlhdr;
uint32 newlen;
Size freespace = 0;
RelFileNode target_node;
BlockNumber blkno;
ItemPointerData target_tid;
XLogRedoAction action;
XLogRecGetBlockTag(record, 0, &target_node, NULL, &blkno);
ItemPointerSetBlockNumber(&target_tid, blkno);
ItemPointerSetOffsetNumber(&target_tid, xlrec->offnum);
/*
* The visibility map may need to be fixed even if the heap page is
* already up-to-date.
*/
if (xlrec->flags & XLH_INSERT_ALL_VISIBLE_CLEARED)
{
Relation reln = CreateFakeRelcacheEntry(target_node);
Buffer vmbuffer = InvalidBuffer;
visibilitymap_pin(reln, blkno, &vmbuffer);
visibilitymap_clear(reln, blkno, vmbuffer, VISIBILITYMAP_VALID_BITS);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
/*
* If we inserted the first and only tuple on the page, re-initialize the
* page from scratch.
*/
if (XLogRecGetInfo(record) & XLOG_HEAP_INIT_PAGE)
{
buffer = XLogInitBufferForRedo(record, 0);
page = BufferGetPage(buffer);
PageInit(page, BufferGetPageSize(buffer), 0);
action = BLK_NEEDS_REDO;
}
else
action = XLogReadBufferForRedo(record, 0, &buffer);
if (action == BLK_NEEDS_REDO)
{
Size datalen;
char *data;
page = BufferGetPage(buffer);
if (PageGetMaxOffsetNumber(page) + 1 < xlrec->offnum)
elog(PANIC, "invalid max offset number");
data = XLogRecGetBlockData(record, 0, &datalen);
newlen = datalen - SizeOfHeapHeader;
Assert(datalen > SizeOfHeapHeader && newlen <= MaxHeapTupleSize);
memcpy((char *) &xlhdr, data, SizeOfHeapHeader);
data += SizeOfHeapHeader;
htup = &tbuf.hdr;
MemSet((char *) htup, 0, SizeofHeapTupleHeader);
/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
memcpy((char *) htup + SizeofHeapTupleHeader,
data,
newlen);
newlen += SizeofHeapTupleHeader;
htup->t_infomask2 = xlhdr.t_infomask2;
htup->t_infomask = xlhdr.t_infomask;
htup->t_hoff = xlhdr.t_hoff;
HeapTupleHeaderSetXmin(htup, XLogRecGetXid(record));
HeapTupleHeaderSetCmin(htup, FirstCommandId);
htup->t_ctid = target_tid;
if (PageAddItem(page, (Item) htup, newlen, xlrec->offnum,
true, true) == InvalidOffsetNumber)
elog(PANIC, "failed to add tuple");
freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */
PageSetLSN(page, lsn);
if (xlrec->flags & XLH_INSERT_ALL_VISIBLE_CLEARED)
PageClearAllVisible(page);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
/*
* If the page is running low on free space, update the FSM as well.
* Arbitrarily, our definition of "low" is less than 20%. We can't do much
* better than that without knowing the fill-factor for the table.
*
* XXX: Don't do this if the page was restored from full page image. We
* don't bother to update the FSM in that case, it doesn't need to be
* totally accurate anyway.
*/
if (action == BLK_NEEDS_REDO && freespace < BLCKSZ / 5)
XLogRecordPageWithFreeSpace(target_node, blkno, freespace);
}
/*
* Handles MULTI_INSERT record type.
*/
static void
heap_xlog_multi_insert(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_multi_insert *xlrec;
RelFileNode rnode;
BlockNumber blkno;
Buffer buffer;
Page page;
union
{
HeapTupleHeaderData hdr;
char data[MaxHeapTupleSize];
} tbuf;
HeapTupleHeader htup;
uint32 newlen;
Size freespace = 0;
int i;
bool isinit = (XLogRecGetInfo(record) & XLOG_HEAP_INIT_PAGE) != 0;
XLogRedoAction action;
/*
* Insertion doesn't overwrite MVCC data, so no conflict processing is
* required.
*/
xlrec = (xl_heap_multi_insert *) XLogRecGetData(record);
XLogRecGetBlockTag(record, 0, &rnode, NULL, &blkno);
/*
* The visibility map may need to be fixed even if the heap page is
* already up-to-date.
*/
if (xlrec->flags & XLH_INSERT_ALL_VISIBLE_CLEARED)
{
Relation reln = CreateFakeRelcacheEntry(rnode);
Buffer vmbuffer = InvalidBuffer;
visibilitymap_pin(reln, blkno, &vmbuffer);
visibilitymap_clear(reln, blkno, vmbuffer, VISIBILITYMAP_VALID_BITS);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
if (isinit)
{
buffer = XLogInitBufferForRedo(record, 0);
page = BufferGetPage(buffer);
PageInit(page, BufferGetPageSize(buffer), 0);
action = BLK_NEEDS_REDO;
}
else
action = XLogReadBufferForRedo(record, 0, &buffer);
if (action == BLK_NEEDS_REDO)
{
char *tupdata;
char *endptr;
Size len;
/* Tuples are stored as block data */
tupdata = XLogRecGetBlockData(record, 0, &len);
endptr = tupdata + len;
page = (Page) BufferGetPage(buffer);
for (i = 0; i < xlrec->ntuples; i++)
{
OffsetNumber offnum;
xl_multi_insert_tuple *xlhdr;
/*
* If we're reinitializing the page, the tuples are stored in
* order from FirstOffsetNumber. Otherwise there's an array of
* offsets in the WAL record, and the tuples come after that.
*/
if (isinit)
offnum = FirstOffsetNumber + i;
else
offnum = xlrec->offsets[i];
if (PageGetMaxOffsetNumber(page) + 1 < offnum)
elog(PANIC, "invalid max offset number");
xlhdr = (xl_multi_insert_tuple *) SHORTALIGN(tupdata);
tupdata = ((char *) xlhdr) + SizeOfMultiInsertTuple;
newlen = xlhdr->datalen;
Assert(newlen <= MaxHeapTupleSize);
htup = &tbuf.hdr;
MemSet((char *) htup, 0, SizeofHeapTupleHeader);
/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
memcpy((char *) htup + SizeofHeapTupleHeader,
(char *) tupdata,
newlen);
tupdata += newlen;
newlen += SizeofHeapTupleHeader;
htup->t_infomask2 = xlhdr->t_infomask2;
htup->t_infomask = xlhdr->t_infomask;
htup->t_hoff = xlhdr->t_hoff;
HeapTupleHeaderSetXmin(htup, XLogRecGetXid(record));
HeapTupleHeaderSetCmin(htup, FirstCommandId);
ItemPointerSetBlockNumber(&htup->t_ctid, blkno);
ItemPointerSetOffsetNumber(&htup->t_ctid, offnum);
offnum = PageAddItem(page, (Item) htup, newlen, offnum, true, true);
if (offnum == InvalidOffsetNumber)
elog(PANIC, "failed to add tuple");
}
if (tupdata != endptr)
elog(PANIC, "total tuple length mismatch");
freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */
PageSetLSN(page, lsn);
if (xlrec->flags & XLH_INSERT_ALL_VISIBLE_CLEARED)
PageClearAllVisible(page);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
/*
* If the page is running low on free space, update the FSM as well.
* Arbitrarily, our definition of "low" is less than 20%. We can't do much
* better than that without knowing the fill-factor for the table.
*
* XXX: Don't do this if the page was restored from full page image. We
* don't bother to update the FSM in that case, it doesn't need to be
* totally accurate anyway.
*/
if (action == BLK_NEEDS_REDO && freespace < BLCKSZ / 5)
XLogRecordPageWithFreeSpace(rnode, blkno, freespace);
}
/*
* Handles UPDATE and HOT_UPDATE
*/
static void
heap_xlog_update(XLogReaderState *record, bool hot_update)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_update *xlrec = (xl_heap_update *) XLogRecGetData(record);
RelFileNode rnode;
BlockNumber oldblk;
BlockNumber newblk;
ItemPointerData newtid;
Buffer obuffer,
nbuffer;
Page page;
OffsetNumber offnum;
ItemId lp = NULL;
HeapTupleData oldtup;
HeapTupleHeader htup;
uint16 prefixlen = 0,
suffixlen = 0;
char *newp;
union
{
HeapTupleHeaderData hdr;
char data[MaxHeapTupleSize];
} tbuf;
xl_heap_header xlhdr;
uint32 newlen;
Size freespace = 0;
XLogRedoAction oldaction;
XLogRedoAction newaction;
/* initialize to keep the compiler quiet */
oldtup.t_data = NULL;
oldtup.t_len = 0;
XLogRecGetBlockTag(record, 0, &rnode, NULL, &newblk);
if (XLogRecGetBlockTag(record, 1, NULL, NULL, &oldblk))
{
/* HOT updates are never done across pages */
Assert(!hot_update);
}
else
oldblk = newblk;
ItemPointerSet(&newtid, newblk, xlrec->new_offnum);
/*
* The visibility map may need to be fixed even if the heap page is
* already up-to-date.
*/
if (xlrec->flags & XLH_UPDATE_OLD_ALL_VISIBLE_CLEARED)
{
Relation reln = CreateFakeRelcacheEntry(rnode);
Buffer vmbuffer = InvalidBuffer;
visibilitymap_pin(reln, oldblk, &vmbuffer);
visibilitymap_clear(reln, oldblk, vmbuffer, VISIBILITYMAP_VALID_BITS);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
/*
* In normal operation, it is important to lock the two pages in
* page-number order, to avoid possible deadlocks against other update
* operations going the other way. However, during WAL replay there can
* be no other update happening, so we don't need to worry about that. But
* we *do* need to worry that we don't expose an inconsistent state to Hot
* Standby queries --- so the original page can't be unlocked before we've
* added the new tuple to the new page.
*/
/* Deal with old tuple version */
oldaction = XLogReadBufferForRedo(record, (oldblk == newblk) ? 0 : 1,
&obuffer);
if (oldaction == BLK_NEEDS_REDO)
{
page = BufferGetPage(obuffer);
offnum = xlrec->old_offnum;
if (PageGetMaxOffsetNumber(page) >= offnum)
lp = PageGetItemId(page, offnum);
if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp))
elog(PANIC, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
oldtup.t_data = htup;
oldtup.t_len = ItemIdGetLength(lp);
htup->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
htup->t_infomask2 &= ~HEAP_KEYS_UPDATED;
if (hot_update)
HeapTupleHeaderSetHotUpdated(htup);
else
HeapTupleHeaderClearHotUpdated(htup);
fix_infomask_from_infobits(xlrec->old_infobits_set, &htup->t_infomask,
&htup->t_infomask2);
HeapTupleHeaderSetXmax(htup, xlrec->old_xmax);
HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
/* Set forward chain link in t_ctid */
htup->t_ctid = newtid;
/* Mark the page as a candidate for pruning */
PageSetPrunable(page, XLogRecGetXid(record));
if (xlrec->flags & XLH_UPDATE_OLD_ALL_VISIBLE_CLEARED)
PageClearAllVisible(page);
PageSetLSN(page, lsn);
MarkBufferDirty(obuffer);
}
/*
* Read the page the new tuple goes into, if different from old.
*/
if (oldblk == newblk)
{
nbuffer = obuffer;
newaction = oldaction;
}
else if (XLogRecGetInfo(record) & XLOG_HEAP_INIT_PAGE)
{
nbuffer = XLogInitBufferForRedo(record, 0);
page = (Page) BufferGetPage(nbuffer);
PageInit(page, BufferGetPageSize(nbuffer), 0);
newaction = BLK_NEEDS_REDO;
}
else
newaction = XLogReadBufferForRedo(record, 0, &nbuffer);
/*
* The visibility map may need to be fixed even if the heap page is
* already up-to-date.
*/
if (xlrec->flags & XLH_UPDATE_NEW_ALL_VISIBLE_CLEARED)
{
Relation reln = CreateFakeRelcacheEntry(rnode);
Buffer vmbuffer = InvalidBuffer;
visibilitymap_pin(reln, newblk, &vmbuffer);
visibilitymap_clear(reln, newblk, vmbuffer, VISIBILITYMAP_VALID_BITS);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
/* Deal with new tuple */
if (newaction == BLK_NEEDS_REDO)
{
char *recdata;
char *recdata_end;
Size datalen;
Size tuplen;
recdata = XLogRecGetBlockData(record, 0, &datalen);
recdata_end = recdata + datalen;
page = BufferGetPage(nbuffer);
offnum = xlrec->new_offnum;
if (PageGetMaxOffsetNumber(page) + 1 < offnum)
elog(PANIC, "invalid max offset number");
if (xlrec->flags & XLH_UPDATE_PREFIX_FROM_OLD)
{
Assert(newblk == oldblk);
memcpy(&prefixlen, recdata, sizeof(uint16));
recdata += sizeof(uint16);
}
if (xlrec->flags & XLH_UPDATE_SUFFIX_FROM_OLD)
{
Assert(newblk == oldblk);
memcpy(&suffixlen, recdata, sizeof(uint16));
recdata += sizeof(uint16);
}
memcpy((char *) &xlhdr, recdata, SizeOfHeapHeader);
recdata += SizeOfHeapHeader;
tuplen = recdata_end - recdata;
Assert(tuplen <= MaxHeapTupleSize);
htup = &tbuf.hdr;
MemSet((char *) htup, 0, SizeofHeapTupleHeader);
/*
* Reconstruct the new tuple using the prefix and/or suffix from the
* old tuple, and the data stored in the WAL record.
*/
newp = (char *) htup + SizeofHeapTupleHeader;
if (prefixlen > 0)
{
int len;
/* copy bitmap [+ padding] [+ oid] from WAL record */
len = xlhdr.t_hoff - SizeofHeapTupleHeader;
memcpy(newp, recdata, len);
recdata += len;
newp += len;
/* copy prefix from old tuple */
memcpy(newp, (char *) oldtup.t_data + oldtup.t_data->t_hoff, prefixlen);
newp += prefixlen;
/* copy new tuple data from WAL record */
len = tuplen - (xlhdr.t_hoff - SizeofHeapTupleHeader);
memcpy(newp, recdata, len);
recdata += len;
newp += len;
}
else
{
/*
* copy bitmap [+ padding] [+ oid] + data from record, all in one
* go
*/
memcpy(newp, recdata, tuplen);
recdata += tuplen;
newp += tuplen;
}
Assert(recdata == recdata_end);
/* copy suffix from old tuple */
if (suffixlen > 0)
memcpy(newp, (char *) oldtup.t_data + oldtup.t_len - suffixlen, suffixlen);
newlen = SizeofHeapTupleHeader + tuplen + prefixlen + suffixlen;
htup->t_infomask2 = xlhdr.t_infomask2;
htup->t_infomask = xlhdr.t_infomask;
htup->t_hoff = xlhdr.t_hoff;
HeapTupleHeaderSetXmin(htup, XLogRecGetXid(record));
HeapTupleHeaderSetCmin(htup, FirstCommandId);
HeapTupleHeaderSetXmax(htup, xlrec->new_xmax);
/* Make sure there is no forward chain link in t_ctid */
htup->t_ctid = newtid;
offnum = PageAddItem(page, (Item) htup, newlen, offnum, true, true);
if (offnum == InvalidOffsetNumber)
elog(PANIC, "failed to add tuple");
if (xlrec->flags & XLH_UPDATE_NEW_ALL_VISIBLE_CLEARED)
PageClearAllVisible(page);
freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */
PageSetLSN(page, lsn);
MarkBufferDirty(nbuffer);
}
if (BufferIsValid(nbuffer) && nbuffer != obuffer)
UnlockReleaseBuffer(nbuffer);
if (BufferIsValid(obuffer))
UnlockReleaseBuffer(obuffer);
/*
* If the new page is running low on free space, update the FSM as well.
* Arbitrarily, our definition of "low" is less than 20%. We can't do much
* better than that without knowing the fill-factor for the table.
*
* However, don't update the FSM on HOT updates, because after crash
* recovery, either the old or the new tuple will certainly be dead and
* prunable. After pruning, the page will have roughly as much free space
* as it did before the update, assuming the new tuple is about the same
* size as the old one.
*
* XXX: Don't do this if the page was restored from full page image. We
* don't bother to update the FSM in that case, it doesn't need to be
* totally accurate anyway.
*/
if (newaction == BLK_NEEDS_REDO && !hot_update && freespace < BLCKSZ / 5)
XLogRecordPageWithFreeSpace(rnode, newblk, freespace);
}
static void
heap_xlog_confirm(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_confirm *xlrec = (xl_heap_confirm *) XLogRecGetData(record);
Buffer buffer;
Page page;
OffsetNumber offnum;
ItemId lp = NULL;
HeapTupleHeader htup;
if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
{
page = BufferGetPage(buffer);
offnum = xlrec->offnum;
if (PageGetMaxOffsetNumber(page) >= offnum)
lp = PageGetItemId(page, offnum);
if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp))
elog(PANIC, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
/*
* Confirm tuple as actually inserted
*/
ItemPointerSet(&htup->t_ctid, BufferGetBlockNumber(buffer), offnum);
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
}
static void
heap_xlog_lock(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_lock *xlrec = (xl_heap_lock *) XLogRecGetData(record);
Buffer buffer;
Page page;
OffsetNumber offnum;
ItemId lp = NULL;
HeapTupleHeader htup;
/*
* The visibility map may need to be fixed even if the heap page is
* already up-to-date.
*/
if (xlrec->flags & XLH_LOCK_ALL_FROZEN_CLEARED)
{
RelFileNode rnode;
Buffer vmbuffer = InvalidBuffer;
BlockNumber block;
Relation reln;
XLogRecGetBlockTag(record, 0, &rnode, NULL, &block);
reln = CreateFakeRelcacheEntry(rnode);
visibilitymap_pin(reln, block, &vmbuffer);
visibilitymap_clear(reln, block, vmbuffer, VISIBILITYMAP_ALL_FROZEN);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
{
page = (Page) BufferGetPage(buffer);
offnum = xlrec->offnum;
if (PageGetMaxOffsetNumber(page) >= offnum)
lp = PageGetItemId(page, offnum);
if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp))
elog(PANIC, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
htup->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
htup->t_infomask2 &= ~HEAP_KEYS_UPDATED;
fix_infomask_from_infobits(xlrec->infobits_set, &htup->t_infomask,
&htup->t_infomask2);
/*
* Clear relevant update flags, but only if the modified infomask says
* there's no update.
*/
if (HEAP_XMAX_IS_LOCKED_ONLY(htup->t_infomask))
{
HeapTupleHeaderClearHotUpdated(htup);
/* Make sure there is no forward chain link in t_ctid */
ItemPointerSet(&htup->t_ctid,
BufferGetBlockNumber(buffer),
offnum);
}
HeapTupleHeaderSetXmax(htup, xlrec->locking_xid);
HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
}
static void
heap_xlog_lock_updated(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_lock_updated *xlrec;
Buffer buffer;
Page page;
OffsetNumber offnum;
ItemId lp = NULL;
HeapTupleHeader htup;
xlrec = (xl_heap_lock_updated *) XLogRecGetData(record);
/*
* The visibility map may need to be fixed even if the heap page is
* already up-to-date.
*/
if (xlrec->flags & XLH_LOCK_ALL_FROZEN_CLEARED)
{
RelFileNode rnode;
Buffer vmbuffer = InvalidBuffer;
BlockNumber block;
Relation reln;
XLogRecGetBlockTag(record, 0, &rnode, NULL, &block);
reln = CreateFakeRelcacheEntry(rnode);
visibilitymap_pin(reln, block, &vmbuffer);
visibilitymap_clear(reln, block, vmbuffer, VISIBILITYMAP_ALL_FROZEN);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
}
if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
{
page = BufferGetPage(buffer);
offnum = xlrec->offnum;
if (PageGetMaxOffsetNumber(page) >= offnum)
lp = PageGetItemId(page, offnum);
if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp))
elog(PANIC, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
htup->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);
htup->t_infomask2 &= ~HEAP_KEYS_UPDATED;
fix_infomask_from_infobits(xlrec->infobits_set, &htup->t_infomask,
&htup->t_infomask2);
HeapTupleHeaderSetXmax(htup, xlrec->xmax);
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
}
static void
heap_xlog_inplace(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
xl_heap_inplace *xlrec = (xl_heap_inplace *) XLogRecGetData(record);
Buffer buffer;
Page page;
OffsetNumber offnum;
ItemId lp = NULL;
HeapTupleHeader htup;
uint32 oldlen;
Size newlen;
if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
{
char *newtup = XLogRecGetBlockData(record, 0, &newlen);
page = BufferGetPage(buffer);
offnum = xlrec->offnum;
if (PageGetMaxOffsetNumber(page) >= offnum)
lp = PageGetItemId(page, offnum);
if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsNormal(lp))
elog(PANIC, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
oldlen = ItemIdGetLength(lp) - htup->t_hoff;
if (oldlen != newlen)
elog(PANIC, "wrong tuple length");
memcpy((char *) htup + htup->t_hoff, newtup, newlen);
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
}
if (BufferIsValid(buffer))
UnlockReleaseBuffer(buffer);
}
void
heap_redo(XLogReaderState *record)
{
uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
/*
* These operations don't overwrite MVCC data so no conflict processing is
* required. The ones in heap2 rmgr do.
*/
switch (info & XLOG_HEAP_OPMASK)
{
case XLOG_HEAP_INSERT:
heap_xlog_insert(record);
break;
case XLOG_HEAP_DELETE:
heap_xlog_delete(record);
break;
case XLOG_HEAP_UPDATE:
heap_xlog_update(record, false);
break;
case XLOG_HEAP_TRUNCATE:
/*
* TRUNCATE is a no-op because the actions are already logged as
* SMGR WAL records. TRUNCATE WAL record only exists for logical
* decoding.
*/
break;
case XLOG_HEAP_HOT_UPDATE:
heap_xlog_update(record, true);
break;
case XLOG_HEAP_CONFIRM:
heap_xlog_confirm(record);
break;
case XLOG_HEAP_LOCK:
heap_xlog_lock(record);
break;
case XLOG_HEAP_INPLACE:
heap_xlog_inplace(record);
break;
default:
elog(PANIC, "heap_redo: unknown op code %u", info);
}
}
void
heap2_redo(XLogReaderState *record)
{
uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
switch (info & XLOG_HEAP_OPMASK)
{
case XLOG_HEAP2_CLEAN:
heap_xlog_clean(record);
break;
case XLOG_HEAP2_FREEZE_PAGE:
heap_xlog_freeze_page(record);
break;
case XLOG_HEAP2_CLEANUP_INFO:
heap_xlog_cleanup_info(record);
break;
case XLOG_HEAP2_VISIBLE:
heap_xlog_visible(record);
break;
case XLOG_HEAP2_MULTI_INSERT:
heap_xlog_multi_insert(record);
break;
case XLOG_HEAP2_LOCK_UPDATED:
heap_xlog_lock_updated(record);
break;
case XLOG_HEAP2_NEW_CID:
/*
* Nothing to do on a real replay, only used during logical
* decoding.
*/
break;
case XLOG_HEAP2_REWRITE:
heap_xlog_logical_rewrite(record);
break;
default:
elog(PANIC, "heap2_redo: unknown op code %u", info);
}
}
/*
* heap_sync - sync a heap, for use when no WAL has been written
*
* This forces the heap contents (including TOAST heap if any) down to disk.
* If we skipped using WAL, and WAL is otherwise needed, we must force the
* relation down to disk before it's safe to commit the transaction. This
* requires writing out any dirty buffers and then doing a forced fsync.
*
* Indexes are not touched. (Currently, index operations associated with
* the commands that use this are WAL-logged and so do not need fsync.
* That behavior might change someday, but in any case it's likely that
* any fsync decisions required would be per-index and hence not appropriate
* to be done here.)
*/
void
heap_sync(Relation rel)
{
/* non-WAL-logged tables never need fsync */
if (!RelationNeedsWAL(rel))
return;
/* main heap */
FlushRelationBuffers(rel);
/* FlushRelationBuffers will have opened rd_smgr */
smgrimmedsync(rel->rd_smgr, MAIN_FORKNUM);
/* FSM is not critical, don't bother syncing it */
/* toast heap, if any */
if (OidIsValid(rel->rd_rel->reltoastrelid))
{
Relation toastrel;
toastrel = table_open(rel->rd_rel->reltoastrelid, AccessShareLock);
FlushRelationBuffers(toastrel);
smgrimmedsync(toastrel->rd_smgr, MAIN_FORKNUM);
table_close(toastrel, AccessShareLock);
}
}
/*
* Mask a heap page before performing consistency checks on it.
*/
void
heap_mask(char *pagedata, BlockNumber blkno)
{
Page page = (Page) pagedata;
OffsetNumber off;
mask_page_lsn_and_checksum(page);
mask_page_hint_bits(page);
mask_unused_space(page);
for (off = 1; off <= PageGetMaxOffsetNumber(page); off++)
{
ItemId iid = PageGetItemId(page, off);
char *page_item;
page_item = (char *) (page + ItemIdGetOffset(iid));
if (ItemIdIsNormal(iid))
{
HeapTupleHeader page_htup = (HeapTupleHeader) page_item;
/*
* If xmin of a tuple is not yet frozen, we should ignore
* differences in hint bits, since they can be set without
* emitting WAL.
*/
if (!HeapTupleHeaderXminFrozen(page_htup))
page_htup->t_infomask &= ~HEAP_XACT_MASK;
else
{
/* Still we need to mask xmax hint bits. */
page_htup->t_infomask &= ~HEAP_XMAX_INVALID;
page_htup->t_infomask &= ~HEAP_XMAX_COMMITTED;
}
/* mask out GPDB specific hint-bits */
page_htup->t_infomask2 &= ~HEAP_XMIN_DISTRIBUTED_SNAPSHOT_IGNORE;
page_htup->t_infomask2 &= ~HEAP_XMAX_DISTRIBUTED_SNAPSHOT_IGNORE;
/*
* During replay, we set Command Id to FirstCommandId. Hence, mask
* it. See heap_xlog_insert() for details.
*/
page_htup->t_choice.t_heap.t_field3.t_cid = MASK_MARKER;
/*
* For a speculative tuple, heap_insert() does not set ctid in the
* caller-passed heap tuple itself, leaving the ctid field to
* contain a speculative token value - a per-backend monotonically
* increasing identifier. Besides, it does not WAL-log ctid under
* any circumstances.
*
* During redo, heap_xlog_insert() sets t_ctid to current block
* number and self offset number. It doesn't care about any
* speculative insertions in master. Hence, we set t_ctid to
* current block number and self offset number to ignore any
* inconsistency.
*/
if (HeapTupleHeaderIsSpeculative(page_htup))
ItemPointerSet(&page_htup->t_ctid, blkno, off);
/*
* NB: Not ignoring ctid changes due to the tuple having moved
* (i.e. HeapTupleHeaderIndicatesMovedPartitions), because that's
* important information that needs to be in-sync between primary
* and standby, and thus is WAL logged.
*/
}
/*
* Ignore any padding bytes after the tuple, when the length of the
* item is not MAXALIGNed.
*/
if (ItemIdHasStorage(iid))
{
int len = ItemIdGetLength(iid);
int padlen = MAXALIGN(len) - len;
if (padlen > 0)
memset(page_item + len, MASK_MARKER, padlen);
}
}
}
相关信息
相关文章
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
8、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦