greenplumn heapam_handler 源码
greenplumn heapam_handler 代码
文件路径：/src/backend/access/heap/heapam_handler.c
/*-------------------------------------------------------------------------
*
* heapam_handler.c
* heap table 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_handler.c
*
*
* NOTES
* This files wires up the lower level heapam.c et al routines with the
* tableam abstraction.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <math.h>
#include "miscadmin.h"
#include "access/genam.h"
#include "access/heapam.h"
#include "access/multixact.h"
#include "access/rewriteheap.h"
#include "access/tableam.h"
#include "access/tsmapi.h"
#include "access/tuptoaster.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/index.h"
#include "catalog/storage.h"
#include "catalog/storage_xlog.h"
#include "commands/progress.h"
#include "commands/vacuum.h"
#include "executor/executor.h"
#include "optimizer/plancat.h"
#include "pgstat.h"
#include "storage/bufmgr.h"
#include "storage/bufpage.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/predicate.h"
#include "storage/procarray.h"
#include "storage/smgr.h"
#include "utils/builtins.h"
#include "utils/rel.h"
static void reform_and_rewrite_tuple(HeapTuple tuple,
Relation OldHeap, Relation NewHeap,
Datum *values, bool *isnull, RewriteState rwstate);
static bool SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer,
HeapTuple tuple,
OffsetNumber tupoffset);
static BlockNumber heapam_scan_get_blocks_done(HeapScanDesc hscan);
static const TableAmRoutine heapam_methods;
/* ------------------------------------------------------------------------
* Slot related callbacks for heap AM
* ------------------------------------------------------------------------
*/
static const TupleTableSlotOps *
heapam_slot_callbacks(Relation relation)
{
return &TTSOpsBufferHeapTuple;
}
/* ------------------------------------------------------------------------
* Index Scan Callbacks for heap AM
* ------------------------------------------------------------------------
*/
static IndexFetchTableData *
heapam_index_fetch_begin(Relation rel)
{
IndexFetchHeapData *hscan = palloc0(sizeof(IndexFetchHeapData));
hscan->xs_base.rel = rel;
hscan->xs_cbuf = InvalidBuffer;
return &hscan->xs_base;
}
static void
heapam_index_fetch_reset(IndexFetchTableData *scan)
{
IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan;
if (BufferIsValid(hscan->xs_cbuf))
{
ReleaseBuffer(hscan->xs_cbuf);
hscan->xs_cbuf = InvalidBuffer;
}
}
static void
heapam_index_fetch_end(IndexFetchTableData *scan)
{
IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan;
heapam_index_fetch_reset(scan);
pfree(hscan);
}
static bool
heapam_index_fetch_tuple(struct IndexFetchTableData *scan,
ItemPointer tid,
Snapshot snapshot,
TupleTableSlot *slot,
bool *call_again, bool *all_dead)
{
IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan;
BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot;
bool got_heap_tuple;
Assert(TTS_IS_BUFFERTUPLE(slot));
/* We can skip the buffer-switching logic if we're in mid-HOT chain. */
if (!*call_again)
{
/* Switch to correct buffer if we don't have it already */
Buffer prev_buf = hscan->xs_cbuf;
hscan->xs_cbuf = ReleaseAndReadBuffer(hscan->xs_cbuf,
hscan->xs_base.rel,
ItemPointerGetBlockNumber(tid));
/*
* Prune page, but only if we weren't already on this page
*/
if (prev_buf != hscan->xs_cbuf)
heap_page_prune_opt(hscan->xs_base.rel, hscan->xs_cbuf);
}
/* Obtain share-lock on the buffer so we can examine visibility */
LockBuffer(hscan->xs_cbuf, BUFFER_LOCK_SHARE);
got_heap_tuple = heap_hot_search_buffer(tid,
hscan->xs_base.rel,
hscan->xs_cbuf,
snapshot,
&bslot->base.tupdata,
all_dead,
!*call_again);
bslot->base.tupdata.t_self = *tid;
LockBuffer(hscan->xs_cbuf, BUFFER_LOCK_UNLOCK);
if (got_heap_tuple)
{
/*
* Only in a non-MVCC snapshot can more than one member of the HOT
* chain be visible.
*/
*call_again = !IsMVCCSnapshot(snapshot);
slot->tts_tableOid = RelationGetRelid(scan->rel);
ExecStoreBufferHeapTuple(&bslot->base.tupdata, slot, hscan->xs_cbuf);
}
else
{
/* We've reached the end of the HOT chain. */
*call_again = false;
}
return got_heap_tuple;
}
/* ------------------------------------------------------------------------
* Callbacks for non-modifying operations on individual tuples for heap AM
* ------------------------------------------------------------------------
*/
static bool
heapam_fetch_row_version(Relation relation,
ItemPointer tid,
Snapshot snapshot,
TupleTableSlot *slot)
{
BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot;
Buffer buffer;
Assert(TTS_IS_BUFFERTUPLE(slot));
bslot->base.tupdata.t_self = *tid;
if (heap_fetch(relation, snapshot, &bslot->base.tupdata, &buffer))
{
/* store in slot, transferring existing pin */
ExecStorePinnedBufferHeapTuple(&bslot->base.tupdata, slot, buffer);
slot->tts_tableOid = RelationGetRelid(relation);
return true;
}
return false;
}
static bool
heapam_tuple_tid_valid(TableScanDesc scan, ItemPointer tid)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
return ItemPointerIsValid(tid) &&
ItemPointerGetBlockNumber(tid) < hscan->rs_nblocks;
}
static bool
heapam_tuple_satisfies_snapshot(Relation rel, TupleTableSlot *slot,
Snapshot snapshot)
{
BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot;
bool res;
Assert(TTS_IS_BUFFERTUPLE(slot));
Assert(BufferIsValid(bslot->buffer));
/*
* We need buffer pin and lock to call HeapTupleSatisfiesVisibility.
* Caller should be holding pin, but not lock.
*/
LockBuffer(bslot->buffer, BUFFER_LOCK_SHARE);
res = HeapTupleSatisfiesVisibility(rel, bslot->base.tuple, snapshot,
bslot->buffer);
LockBuffer(bslot->buffer, BUFFER_LOCK_UNLOCK);
return res;
}
/* ----------------------------------------------------------------------------
* Functions for manipulations of physical tuples for heap AM.
* ----------------------------------------------------------------------------
*/
static void
heapam_tuple_insert(Relation relation, TupleTableSlot *slot, CommandId cid,
int options, BulkInsertState bistate)
{
bool shouldFree = true;
HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree);
TransactionId xid = GetCurrentTransactionId();
/* Update the tuple with table oid */
slot->tts_tableOid = RelationGetRelid(relation);
tuple->t_tableOid = slot->tts_tableOid;
/* Perform the insertion, and copy the resulting ItemPointer */
heap_insert(relation, tuple, cid, options, bistate, xid);
ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
if (shouldFree)
pfree(tuple);
}
static void
heapam_tuple_insert_speculative(Relation relation, TupleTableSlot *slot,
CommandId cid, int options,
BulkInsertState bistate, uint32 specToken)
{
bool shouldFree = true;
HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree);
TransactionId xid = GetCurrentTransactionId();
/* Update the tuple with table oid */
slot->tts_tableOid = RelationGetRelid(relation);
tuple->t_tableOid = slot->tts_tableOid;
HeapTupleHeaderSetSpeculativeToken(tuple->t_data, specToken);
options |= HEAP_INSERT_SPECULATIVE;
/* Perform the insertion, and copy the resulting ItemPointer */
heap_insert(relation, tuple, cid, options, bistate, xid);
ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
if (shouldFree)
pfree(tuple);
}
static void
heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
uint32 specToken, bool succeeded)
{
bool shouldFree = true;
HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree);
/* adjust the tuple's state accordingly */
if (succeeded)
heap_finish_speculative(relation, &slot->tts_tid);
else
heap_abort_speculative(relation, &slot->tts_tid);
if (shouldFree)
pfree(tuple);
}
static TM_Result
heapam_tuple_delete(Relation relation, ItemPointer tid, CommandId cid,
Snapshot snapshot, Snapshot crosscheck, bool wait,
TM_FailureData *tmfd, bool changingPart)
{
/*
* Currently Deleting of index tuples are handled at vacuum, in case if
* the storage itself is cleaning the dead tuples by itself, it is the
* time to call the index tuple deletion also.
*/
return heap_delete(relation, tid, cid, crosscheck, wait, tmfd, changingPart);
}
static TM_Result
heapam_tuple_update(Relation relation, ItemPointer otid, TupleTableSlot *slot,
CommandId cid, Snapshot snapshot, Snapshot crosscheck,
bool wait, TM_FailureData *tmfd,
LockTupleMode *lockmode, bool *update_indexes)
{
bool shouldFree = true;
HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree);
TM_Result result;
/* Update the tuple with table oid */
slot->tts_tableOid = RelationGetRelid(relation);
tuple->t_tableOid = slot->tts_tableOid;
result = heap_update(relation, otid, tuple, cid, crosscheck, wait,
tmfd, lockmode);
ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
/*
* Decide whether new index entries are needed for the tuple
*
* Note: heap_update returns the tid (location) of the new tuple in the
* t_self field.
*
* If it's a HOT update, we mustn't insert new index entries.
*/
*update_indexes = result == TM_Ok && !HeapTupleIsHeapOnly(tuple);
if (shouldFree)
pfree(tuple);
return result;
}
static TM_Result
heapam_tuple_lock(Relation relation, ItemPointer tid, Snapshot snapshot,
TupleTableSlot *slot, CommandId cid, LockTupleMode mode,
LockWaitPolicy wait_policy, uint8 flags,
TM_FailureData *tmfd)
{
BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot;
TM_Result result;
Buffer buffer;
HeapTuple tuple = &bslot->base.tupdata;
bool follow_updates;
follow_updates = (flags & TUPLE_LOCK_FLAG_LOCK_UPDATE_IN_PROGRESS) != 0;
tmfd->traversed = false;
Assert(TTS_IS_BUFFERTUPLE(slot));
tuple_lock_retry:
tuple->t_self = *tid;
result = heap_lock_tuple(relation, tuple, cid, mode, wait_policy,
follow_updates, &buffer, tmfd);
if (result == TM_Updated &&
(flags & TUPLE_LOCK_FLAG_FIND_LAST_VERSION))
{
ReleaseBuffer(buffer);
/* Should not encounter speculative tuple on recheck */
Assert(!HeapTupleHeaderIsSpeculative(tuple->t_data));
if (!ItemPointerEquals(&tmfd->ctid, &tuple->t_self))
{
SnapshotData SnapshotDirty;
TransactionId priorXmax;
/* it was updated, so look at the updated version */
*tid = tmfd->ctid;
/* updated row should have xmin matching this xmax */
priorXmax = tmfd->xmax;
/* signal that a tuple later in the chain is getting locked */
tmfd->traversed = true;
/*
* fetch target tuple
*
* Loop here to deal with updated or busy tuples
*/
InitDirtySnapshot(SnapshotDirty);
for (;;)
{
/*
* Greenplum specific error message
* Split-update is used to implment update on distribute keys
* of hash partitioned table in Greenplum. UPDATE on distkeys
* is similar to upstream's UPDATE on partition keys. We will
* store bit info in the tuple's head to mark it is split-updated,
* so the blocked transaction which also wants to update or delete
* the same tuple will abort. We re-use upstream's code to implement
* this, just modify a little of the following error message.
*/
if (ItemPointerIndicatesMovedPartitions(tid))
ereport(ERROR,
(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
errmsg("tuple to be locked was already moved to another partition or segment due to concurrent update")));
tuple->t_self = *tid;
if (heap_fetch(relation, &SnapshotDirty, tuple, &buffer))
{
/*
* If xmin isn't what we're expecting, the slot must have
* been recycled and reused for an unrelated tuple. This
* implies that the latest version of the row was deleted,
* so we need do nothing. (Should be safe to examine xmin
* without getting buffer's content lock. We assume
* reading a TransactionId to be atomic, and Xmin never
* changes in an existing tuple, except to invalid or
* frozen, and neither of those can match priorXmax.)
*/
if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple->t_data),
priorXmax))
{
ReleaseBuffer(buffer);
return TM_Deleted;
}
/* otherwise xmin should not be dirty... */
if (TransactionIdIsValid(SnapshotDirty.xmin))
elog(ERROR, "t_xmin is uncommitted in tuple to be updated");
/*
* If tuple is being updated by other transaction then we
* have to wait for its commit/abort, or die trying.
*/
if (TransactionIdIsValid(SnapshotDirty.xmax))
{
ReleaseBuffer(buffer);
switch (wait_policy)
{
case LockWaitBlock:
XactLockTableWait(SnapshotDirty.xmax,
relation, &tuple->t_self,
XLTW_FetchUpdated);
break;
case LockWaitSkip:
if (!ConditionalXactLockTableWait(SnapshotDirty.xmax))
/* skip instead of waiting */
return TM_WouldBlock;
break;
case LockWaitError:
if (!ConditionalXactLockTableWait(SnapshotDirty.xmax))
ereport(ERROR,
(errcode(ERRCODE_LOCK_NOT_AVAILABLE),
errmsg("could not obtain lock on row in relation \"%s\"",
RelationGetRelationName(relation))));
break;
}
continue; /* loop back to repeat heap_fetch */
}
/*
* If tuple was inserted by our own transaction, we have
* to check cmin against cid: cmin >= current CID means
* our command cannot see the tuple, so we should ignore
* it. Otherwise heap_lock_tuple() will throw an error,
* and so would any later attempt to update or delete the
* tuple. (We need not check cmax because
* HeapTupleSatisfiesDirty will consider a tuple deleted
* by our transaction dead, regardless of cmax.) We just
* checked that priorXmax == xmin, so we can test that
* variable instead of doing HeapTupleHeaderGetXmin again.
*/
if (TransactionIdIsCurrentTransactionId(priorXmax) &&
HeapTupleHeaderGetCmin(tuple->t_data) >= cid)
{
tmfd->xmax = priorXmax;
/*
* Cmin is the problematic value, so store that. See
* above.
*/
tmfd->cmax = HeapTupleHeaderGetCmin(tuple->t_data);
ReleaseBuffer(buffer);
return TM_SelfModified;
}
/*
* This is a live tuple, so try to lock it again.
*/
ReleaseBuffer(buffer);
goto tuple_lock_retry;
}
/*
* If the referenced slot was actually empty, the latest
* version of the row must have been deleted, so we need do
* nothing.
*/
if (tuple->t_data == NULL)
{
return TM_Deleted;
}
/*
* As above, if xmin isn't what we're expecting, do nothing.
*/
if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple->t_data),
priorXmax))
{
if (BufferIsValid(buffer))
ReleaseBuffer(buffer);
return TM_Deleted;
}
/*
* If we get here, the tuple was found but failed
* SnapshotDirty. Assuming the xmin is either a committed xact
* or our own xact (as it certainly should be if we're trying
* to modify the tuple), this must mean that the row was
* updated or deleted by either a committed xact or our own
* xact. If it was deleted, we can ignore it; if it was
* updated then chain up to the next version and repeat the
* whole process.
*
* As above, it should be safe to examine xmax and t_ctid
* without the buffer content lock, because they can't be
* changing.
*/
if (ItemPointerEquals(&tuple->t_self, &tuple->t_data->t_ctid))
{
/* deleted, so forget about it */
if (BufferIsValid(buffer))
ReleaseBuffer(buffer);
return TM_Deleted;
}
/* updated, so look at the updated row */
*tid = tuple->t_data->t_ctid;
/* updated row should have xmin matching this xmax */
priorXmax = HeapTupleHeaderGetUpdateXid(tuple->t_data);
if (BufferIsValid(buffer))
ReleaseBuffer(buffer);
/* loop back to fetch next in chain */
}
}
else
{
/* tuple was deleted, so give up */
return TM_Deleted;
}
}
slot->tts_tableOid = RelationGetRelid(relation);
tuple->t_tableOid = slot->tts_tableOid;
/* store in slot, transferring existing pin */
ExecStorePinnedBufferHeapTuple(tuple, slot, buffer);
return result;
}
static void
heapam_finish_bulk_insert(Relation relation, int options)
{
/*
* If we skipped writing WAL, then we need to sync the heap (but not
* indexes since those use WAL anyway / don't go through tableam)
*/
if (options & HEAP_INSERT_SKIP_WAL)
heap_sync(relation);
}
/* ------------------------------------------------------------------------
* DDL related callbacks for heap AM.
* ------------------------------------------------------------------------
*/
static void
heapam_relation_set_new_filenode(Relation rel,
const RelFileNode *newrnode,
char persistence,
TransactionId *freezeXid,
MultiXactId *minmulti)
{
SMgrRelation srel;
/*
* Initialize to the minimum XID that could put tuples in the table. We
* know that no xacts older than RecentXmin are still running, so that
* will do.
*/
*freezeXid = RecentXmin;
/*
* Similarly, initialize the minimum Multixact to the first value that
* could possibly be stored in tuples in the table. Running transactions
* could reuse values from their local cache, so we are careful to
* consider all currently running multis.
*
* XXX this could be refined further, but is it worth the hassle?
*/
*minmulti = GetOldestMultiXactId();
srel = RelationCreateStorage(*newrnode, persistence, SMGR_MD);
/*
* If required, set up an init fork for an unlogged table so that it can
* be correctly reinitialized on restart. An immediate sync is required
* even if the page has been logged, because the write did not go through
* shared_buffers and therefore a concurrent checkpoint may have moved the
* redo pointer past our xlog record. Recovery may as well remove it
* while replaying, for example, XLOG_DBASE_CREATE or XLOG_TBLSPC_CREATE
* record. Therefore, logging is necessary even if wal_level=minimal.
*/
if (persistence == RELPERSISTENCE_UNLOGGED)
{
Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
rel->rd_rel->relkind == RELKIND_MATVIEW ||
rel->rd_rel->relkind == RELKIND_TOASTVALUE ||
rel->rd_rel->relkind == RELKIND_AOSEGMENTS ||
rel->rd_rel->relkind == RELKIND_AOVISIMAP ||
rel->rd_rel->relkind == RELKIND_AOBLOCKDIR);
smgrcreate(srel, INIT_FORKNUM, false);
log_smgrcreate(newrnode, INIT_FORKNUM, SMGR_MD);
smgrimmedsync(srel, INIT_FORKNUM);
}
smgrclose(srel);
}
static void
heapam_relation_nontransactional_truncate(Relation rel)
{
RelationTruncate(rel, 0);
}
static void
heapam_relation_copy_data(Relation rel, const RelFileNode *newrnode)
{
SMgrRelation dstrel;
dstrel = smgropen(*newrnode, rel->rd_backend, SMGR_MD);
RelationOpenSmgr(rel);
/*
* Since we copy the file directly without looking at the shared buffers,
* we'd better first flush out any pages of the source relation that are
* in shared buffers. We assume no new changes will be made while we are
* holding exclusive lock on the rel.
*/
FlushRelationBuffers(rel);
/*
* Create and copy all forks of the relation, and schedule unlinking of
* old physical files.
*
* NOTE: any conflict in relfilenode value will be caught in
* RelationCreateStorage().
*/
RelationCreateStorage(*newrnode, rel->rd_rel->relpersistence, SMGR_MD);
/* copy main fork */
RelationCopyStorage(rel->rd_smgr, dstrel, MAIN_FORKNUM,
rel->rd_rel->relpersistence);
/* copy those extra forks that exist */
for (ForkNumber forkNum = MAIN_FORKNUM + 1;
forkNum <= MAX_FORKNUM; forkNum++)
{
if (smgrexists(rel->rd_smgr, forkNum))
{
smgrcreate(dstrel, forkNum, false);
/*
* WAL log creation if the relation is persistent, or this is the
* init fork of an unlogged relation.
*/
if (rel->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT ||
(rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED &&
forkNum == INIT_FORKNUM))
log_smgrcreate(newrnode, forkNum, SMGR_MD);
RelationCopyStorage(rel->rd_smgr, dstrel, forkNum,
rel->rd_rel->relpersistence);
}
}
/* drop old relation, and close new one */
RelationDropStorage(rel);
smgrclose(dstrel);
}
static void
heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
Relation OldIndex, bool use_sort,
TransactionId OldestXmin,
TransactionId *xid_cutoff,
MultiXactId *multi_cutoff,
double *num_tuples,
double *tups_vacuumed,
double *tups_recently_dead)
{
RewriteState rwstate;
IndexScanDesc indexScan;
TableScanDesc tableScan;
HeapScanDesc heapScan;
bool use_wal;
bool is_system_catalog;
Tuplesortstate *tuplesort;
TupleDesc oldTupDesc = RelationGetDescr(OldHeap);
TupleDesc newTupDesc = RelationGetDescr(NewHeap);
TupleTableSlot *slot;
int natts;
Datum *values;
bool *isnull;
BufferHeapTupleTableSlot *hslot;
/* Remember if it's a system catalog */
is_system_catalog = IsSystemRelation(OldHeap);
/*
* We need to log the copied data in WAL iff WAL archiving/streaming is
* enabled AND it's a WAL-logged rel.
*/
use_wal = XLogIsNeeded() && RelationNeedsWAL(NewHeap);
/* use_wal off requires smgr_targblock be initially invalid */
Assert(RelationGetTargetBlock(NewHeap) == InvalidBlockNumber);
/* Preallocate values/isnull arrays */
natts = newTupDesc->natts;
values = (Datum *) palloc(natts * sizeof(Datum));
isnull = (bool *) palloc(natts * sizeof(bool));
/* Initialize the rewrite operation */
rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin, *xid_cutoff,
*multi_cutoff, use_wal);
/* Set up sorting if wanted */
if (use_sort)
tuplesort = tuplesort_begin_cluster(oldTupDesc, OldIndex,
maintenance_work_mem,
NULL, false);
else
tuplesort = NULL;
/*
* Prepare to scan the OldHeap. To ensure we see recently-dead tuples
* that still need to be copied, we scan with SnapshotAny and use
* HeapTupleSatisfiesVacuum for the visibility test.
*/
if (OldIndex != NULL && !use_sort)
{
const int ci_index[] = {
PROGRESS_CLUSTER_PHASE,
PROGRESS_CLUSTER_INDEX_RELID
};
int64 ci_val[2];
/* Set phase and OIDOldIndex to columns */
ci_val[0] = PROGRESS_CLUSTER_PHASE_INDEX_SCAN_HEAP;
ci_val[1] = RelationGetRelid(OldIndex);
pgstat_progress_update_multi_param(2, ci_index, ci_val);
tableScan = NULL;
heapScan = NULL;
indexScan = index_beginscan(OldHeap, OldIndex, SnapshotAny, 0, 0);
index_rescan(indexScan, NULL, 0, NULL, 0);
}
else
{
/* In scan-and-sort mode and also VACUUM FULL, set phase */
pgstat_progress_update_param(PROGRESS_CLUSTER_PHASE,
PROGRESS_CLUSTER_PHASE_SEQ_SCAN_HEAP);
tableScan = table_beginscan(OldHeap, SnapshotAny, 0, (ScanKey) NULL);
heapScan = (HeapScanDesc) tableScan;
indexScan = NULL;
/* Set total heap blocks */
pgstat_progress_update_param(PROGRESS_CLUSTER_TOTAL_HEAP_BLKS,
heapScan->rs_nblocks);
}
slot = table_slot_create(OldHeap, NULL);
hslot = (BufferHeapTupleTableSlot *) slot;
/*
* Scan through the OldHeap, either in OldIndex order or sequentially;
* copy each tuple into the NewHeap, or transiently to the tuplesort
* module. Note that we don't bother sorting dead tuples (they won't get
* to the new table anyway).
*/
for (;;)
{
HeapTuple tuple;
Buffer buf;
bool isdead;
CHECK_FOR_INTERRUPTS();
if (indexScan != NULL)
{
if (!index_getnext_slot(indexScan, ForwardScanDirection, slot))
break;
/* Since we used no scan keys, should never need to recheck */
if (indexScan->xs_recheck)
elog(ERROR, "CLUSTER does not support lossy index conditions");
}
else
{
if (!table_scan_getnextslot(tableScan, ForwardScanDirection, slot))
break;
/*
* In scan-and-sort mode and also VACUUM FULL, set heap blocks
* scanned
*/
pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_BLKS_SCANNED,
heapScan->rs_cblock + 1);
}
tuple = ExecFetchSlotHeapTuple(slot, false, NULL);
buf = hslot->buffer;
LockBuffer(buf, BUFFER_LOCK_SHARE);
switch (HeapTupleSatisfiesVacuum(OldHeap, tuple, OldestXmin, buf))
{
case HEAPTUPLE_DEAD:
/* Definitely dead */
isdead = true;
break;
case HEAPTUPLE_RECENTLY_DEAD:
*tups_recently_dead += 1;
/* fall through */
case HEAPTUPLE_LIVE:
/* Live or recently dead, must copy it */
isdead = false;
break;
case HEAPTUPLE_INSERT_IN_PROGRESS:
/*
* Since we hold exclusive lock on the relation, normally the
* only way to see this is if it was inserted earlier in our
* own transaction. However, it can happen in system
* catalogs, since we tend to release write lock before commit
* there. Give a warning if neither case applies; but in any
* case we had better copy it.
*/
if (!is_system_catalog &&
!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple->t_data)))
elog(WARNING, "concurrent insert in progress within table \"%s\"",
RelationGetRelationName(OldHeap));
/* treat as live */
isdead = false;
break;
case HEAPTUPLE_DELETE_IN_PROGRESS:
/*
* Similar situation to INSERT_IN_PROGRESS case.
*/
if (!is_system_catalog &&
!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(tuple->t_data)))
elog(WARNING, "concurrent delete in progress within table \"%s\"",
RelationGetRelationName(OldHeap));
/* treat as recently dead */
*tups_recently_dead += 1;
isdead = false;
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
isdead = false; /* keep compiler quiet */
break;
}
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
if (isdead)
{
*tups_vacuumed += 1;
/* heap rewrite module still needs to see it... */
if (rewrite_heap_dead_tuple(rwstate, tuple))
{
/* A previous recently-dead tuple is now known dead */
*tups_vacuumed += 1;
*tups_recently_dead -= 1;
}
continue;
}
*num_tuples += 1;
if (tuplesort != NULL)
{
tuplesort_putheaptuple(tuplesort, tuple);
/*
* In scan-and-sort mode, report increase in number of tuples
* scanned
*/
pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_TUPLES_SCANNED,
*num_tuples);
}
else
{
const int ct_index[] = {
PROGRESS_CLUSTER_HEAP_TUPLES_SCANNED,
PROGRESS_CLUSTER_HEAP_TUPLES_WRITTEN
};
int64 ct_val[2];
reform_and_rewrite_tuple(tuple, OldHeap, NewHeap,
values, isnull, rwstate);
/*
* In indexscan mode and also VACUUM FULL, report increase in
* number of tuples scanned and written
*/
ct_val[0] = *num_tuples;
ct_val[1] = *num_tuples;
pgstat_progress_update_multi_param(2, ct_index, ct_val);
}
}
if (indexScan != NULL)
index_endscan(indexScan);
if (tableScan != NULL)
table_endscan(tableScan);
if (slot)
ExecDropSingleTupleTableSlot(slot);
/*
* In scan-and-sort mode, complete the sort, then read out all live tuples
* from the tuplestore and write them to the new relation.
*/
if (tuplesort != NULL)
{
double n_tuples = 0;
/* Report that we are now sorting tuples */
pgstat_progress_update_param(PROGRESS_CLUSTER_PHASE,
PROGRESS_CLUSTER_PHASE_SORT_TUPLES);
tuplesort_performsort(tuplesort);
/* Report that we are now writing new heap */
pgstat_progress_update_param(PROGRESS_CLUSTER_PHASE,
PROGRESS_CLUSTER_PHASE_WRITE_NEW_HEAP);
for (;;)
{
HeapTuple tuple;
CHECK_FOR_INTERRUPTS();
tuple = tuplesort_getheaptuple(tuplesort, true);
if (tuple == NULL)
break;
n_tuples += 1;
reform_and_rewrite_tuple(tuple,
OldHeap, NewHeap,
values, isnull,
rwstate);
/* Report n_tuples */
pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_TUPLES_WRITTEN,
n_tuples);
}
tuplesort_end(tuplesort);
}
/* Write out any remaining tuples, and fsync if needed */
end_heap_rewrite(rwstate);
/* Clean up */
pfree(values);
pfree(isnull);
}
static bool
heapam_scan_analyze_next_block(TableScanDesc scan, BlockNumber blockno,
BufferAccessStrategy bstrategy)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
/*
* We must maintain a pin on the target page's buffer to ensure that
* concurrent activity - e.g. HOT pruning - doesn't delete tuples out from
* under us. Hence, pin the page until we are done looking at it. We
* also choose to hold sharelock on the buffer throughout --- we could
* release and re-acquire sharelock for each tuple, but since we aren't
* doing much work per tuple, the extra lock traffic is probably better
* avoided.
*/
hscan->rs_cblock = blockno;
hscan->rs_cindex = FirstOffsetNumber;
hscan->rs_cbuf = ReadBufferExtended(scan->rs_rd, MAIN_FORKNUM,
blockno, RBM_NORMAL, bstrategy);
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
/* in heap all blocks can contain tuples, so always return true */
return true;
}
static bool
heapam_scan_analyze_next_tuple(TableScanDesc scan, TransactionId OldestXmin,
double *liverows, double *deadrows,
TupleTableSlot *slot)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
Page targpage;
OffsetNumber maxoffset;
BufferHeapTupleTableSlot *hslot;
Assert(TTS_IS_BUFFERTUPLE(slot));
hslot = (BufferHeapTupleTableSlot *) slot;
targpage = BufferGetPage(hscan->rs_cbuf);
maxoffset = PageGetMaxOffsetNumber(targpage);
/* Inner loop over all tuples on the selected page */
for (; hscan->rs_cindex <= maxoffset; hscan->rs_cindex++)
{
ItemId itemid;
HeapTuple targtuple = &hslot->base.tupdata;
bool sample_it = false;
itemid = PageGetItemId(targpage, hscan->rs_cindex);
/*
* We ignore unused and redirect line pointers. DEAD line pointers
* should be counted as dead, because we need vacuum to run to get rid
* of them. Note that this rule agrees with the way that
* heap_page_prune() counts things.
*/
if (!ItemIdIsNormal(itemid))
{
if (ItemIdIsDead(itemid))
*deadrows += 1;
continue;
}
ItemPointerSet(&targtuple->t_self, hscan->rs_cblock, hscan->rs_cindex);
targtuple->t_tableOid = RelationGetRelid(scan->rs_rd);
targtuple->t_data = (HeapTupleHeader) PageGetItem(targpage, itemid);
targtuple->t_len = ItemIdGetLength(itemid);
switch (HeapTupleSatisfiesVacuum(hscan->rs_base.rs_rd,
targtuple, OldestXmin,
hscan->rs_cbuf))
{
case HEAPTUPLE_LIVE:
sample_it = true;
*liverows += 1;
break;
case HEAPTUPLE_DEAD:
case HEAPTUPLE_RECENTLY_DEAD:
/* Count dead and recently-dead rows */
*deadrows += 1;
break;
case HEAPTUPLE_INSERT_IN_PROGRESS:
/*
* Insert-in-progress rows are not counted. We assume that
* when the inserting transaction commits or aborts, it will
* send a stats message to increment the proper count. This
* works right only if that transaction ends after we finish
* analyzing the table; if things happen in the other order,
* its stats update will be overwritten by ours. However, the
* error will be large only if the other transaction runs long
* enough to insert many tuples, so assuming it will finish
* after us is the safer option.
*
* A special case is that the inserting transaction might be
* our own. In this case we should count and sample the row,
* to accommodate users who load a table and analyze it in one
* transaction. (pgstat_report_analyze has to adjust the
* numbers we send to the stats collector to make this come
* out right.)
*/
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(targtuple->t_data)))
{
sample_it = true;
*liverows += 1;
}
break;
case HEAPTUPLE_DELETE_IN_PROGRESS:
/*
* We count and sample delete-in-progress rows the same as
* live ones, so that the stats counters come out right if the
* deleting transaction commits after us, per the same
* reasoning given above.
*
* If the delete was done by our own transaction, however, we
* must count the row as dead to make pgstat_report_analyze's
* stats adjustments come out right. (Note: this works out
* properly when the row was both inserted and deleted in our
* xact.)
*
* The net effect of these choices is that we act as though an
* IN_PROGRESS transaction hasn't happened yet, except if it
* is our own transaction, which we assume has happened.
*
* This approach ensures that we behave sanely if we see both
* the pre-image and post-image rows for a row being updated
* by a concurrent transaction: we will sample the pre-image
* but not the post-image. We also get sane results if the
* concurrent transaction never commits.
*/
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(targtuple->t_data)))
*deadrows += 1;
else
{
sample_it = true;
*liverows += 1;
}
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
break;
}
if (sample_it)
{
ExecStoreBufferHeapTuple(targtuple, slot, hscan->rs_cbuf);
hscan->rs_cindex++;
/* note that we leave the buffer locked here! */
return true;
}
}
/* Now release the lock and pin on the page */
UnlockReleaseBuffer(hscan->rs_cbuf);
hscan->rs_cbuf = InvalidBuffer;
/* also prevent old slot contents from having pin on page */
ExecClearTuple(slot);
return false;
}
static double
heapam_index_build_range_scan(Relation heapRelation,
Relation indexRelation,
IndexInfo *indexInfo,
bool allow_sync,
bool anyvisible,
bool progress,
BlockNumber start_blockno,
BlockNumber numblocks,
IndexBuildCallback callback,
void *callback_state,
TableScanDesc scan)
{
HeapScanDesc hscan;
bool is_system_catalog;
bool checking_uniqueness;
HeapTuple heapTuple;
Datum values[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
double reltuples;
ExprState *predicate;
TupleTableSlot *slot;
EState *estate;
ExprContext *econtext;
Snapshot snapshot;
bool need_unregister_snapshot = false;
TransactionId OldestXmin;
BlockNumber previous_blkno = InvalidBlockNumber;
BlockNumber root_blkno = InvalidBlockNumber;
OffsetNumber root_offsets[MaxHeapTuplesPerPage];
/*
* sanity checks
*/
Assert(OidIsValid(indexRelation->rd_rel->relam));
/* Remember if it's a system catalog */
is_system_catalog = IsSystemRelation(heapRelation);
/* See whether we're verifying uniqueness/exclusion properties */
checking_uniqueness = (indexInfo->ii_Unique ||
indexInfo->ii_ExclusionOps != NULL);
/*
* "Any visible" mode is not compatible with uniqueness checks; make sure
* only one of those is requested.
*/
Assert(!(anyvisible && checking_uniqueness));
/*
* Need an EState for evaluation of index expressions and partial-index
* predicates. Also a slot to hold the current tuple.
*/
estate = CreateExecutorState();
econtext = GetPerTupleExprContext(estate);
slot = table_slot_create(heapRelation, NULL);
/* Arrange for econtext's scan tuple to be the tuple under test */
econtext->ecxt_scantuple = slot;
/* Set up execution state for predicate, if any. */
predicate = ExecPrepareQual(indexInfo->ii_Predicate, estate);
/*
* Prepare for scan of the base relation. In a normal index build, we use
* SnapshotAny because we must retrieve all tuples and do our own time
* qual checks (because we have to index RECENTLY_DEAD tuples). In a
* concurrent build, or during bootstrap, we take a regular MVCC snapshot
* and index whatever's live according to that.
*/
OldestXmin = InvalidTransactionId;
/* okay to ignore lazy VACUUMs here */
if (!IsBootstrapProcessingMode() && !indexInfo->ii_Concurrent)
OldestXmin = GetOldestXmin(heapRelation, PROCARRAY_FLAGS_VACUUM);
if (!scan)
{
/*
* Serial index build.
*
* Must begin our own heap scan in this case. We may also need to
* register a snapshot whose lifetime is under our direct control.
*/
if (!TransactionIdIsValid(OldestXmin))
{
snapshot = RegisterSnapshot(GetTransactionSnapshot());
need_unregister_snapshot = true;
}
else
snapshot = SnapshotAny;
scan = table_beginscan_strat(heapRelation, /* relation */
snapshot, /* snapshot */
0, /* number of keys */
NULL, /* scan key */
true, /* buffer access strategy OK */
allow_sync); /* syncscan OK? */
}
else
{
/*
* Parallel index build.
*
* Parallel case never registers/unregisters own snapshot. Snapshot
* is taken from parallel heap scan, and is SnapshotAny or an MVCC
* snapshot, based on same criteria as serial case.
*/
Assert(!IsBootstrapProcessingMode());
Assert(allow_sync);
snapshot = scan->rs_snapshot;
}
hscan = (HeapScanDesc) scan;
/* Publish number of blocks to scan */
if (progress)
{
BlockNumber nblocks;
if (hscan->rs_base.rs_parallel != NULL)
{
ParallelBlockTableScanDesc pbscan;
pbscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
nblocks = pbscan->phs_nblocks;
}
else
nblocks = hscan->rs_nblocks;
pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_TOTAL,
nblocks);
}
/*
* Must call GetOldestXmin() with SnapshotAny. Should never call
* GetOldestXmin() with MVCC snapshot. (It's especially worth checking
* this for parallel builds, since ambuild routines that support parallel
* builds must work these details out for themselves.)
*/
Assert(snapshot == SnapshotAny || IsMVCCSnapshot(snapshot));
Assert(snapshot == SnapshotAny ? TransactionIdIsValid(OldestXmin) :
!TransactionIdIsValid(OldestXmin));
Assert(snapshot == SnapshotAny || !anyvisible);
/* set our scan endpoints */
if (!allow_sync)
heap_setscanlimits(scan, start_blockno, numblocks);
else
{
/* syncscan can only be requested on whole relation */
Assert(start_blockno == 0);
Assert(numblocks == InvalidBlockNumber);
}
reltuples = 0;
/*
* Scan all tuples in the base relation.
*/
while ((heapTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
bool tupleIsAlive;
CHECK_FOR_INTERRUPTS();
/* Report scan progress, if asked to. */
if (progress)
{
BlockNumber blocks_done = heapam_scan_get_blocks_done(hscan);
if (blocks_done != previous_blkno)
{
pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_DONE,
blocks_done);
previous_blkno = blocks_done;
}
}
/*
* When dealing with a HOT-chain of updated tuples, we want to index
* the values of the live tuple (if any), but index it under the TID
* of the chain's root tuple. This approach is necessary to preserve
* the HOT-chain structure in the heap. So we need to be able to find
* the root item offset for every tuple that's in a HOT-chain. When
* first reaching a new page of the relation, call
* heap_get_root_tuples() to build a map of root item offsets on the
* page.
*
* It might look unsafe to use this information across buffer
* lock/unlock. However, we hold ShareLock on the table so no
* ordinary insert/update/delete should occur; and we hold pin on the
* buffer continuously while visiting the page, so no pruning
* operation can occur either.
*
* Also, although our opinions about tuple liveness could change while
* we scan the page (due to concurrent transaction commits/aborts),
* the chain root locations won't, so this info doesn't need to be
* rebuilt after waiting for another transaction.
*
* Note the implied assumption that there is no more than one live
* tuple per HOT-chain --- else we could create more than one index
* entry pointing to the same root tuple.
*/
if (hscan->rs_cblock != root_blkno)
{
Page page = BufferGetPage(hscan->rs_cbuf);
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
heap_get_root_tuples(page, root_offsets);
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
root_blkno = hscan->rs_cblock;
}
if (snapshot == SnapshotAny)
{
/* do our own time qual check */
bool indexIt;
TransactionId xwait;
recheck:
/*
* We could possibly get away with not locking the buffer here,
* since caller should hold ShareLock on the relation, but let's
* be conservative about it. (This remark is still correct even
* with HOT-pruning: our pin on the buffer prevents pruning.)
*/
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
/*
* The criteria for counting a tuple as live in this block need to
* match what analyze.c's heapam_scan_analyze_next_tuple() does,
* otherwise CREATE INDEX and ANALYZE may produce wildly different
* reltuples values, e.g. when there are many recently-dead
* tuples.
*/
switch (HeapTupleSatisfiesVacuum(heapRelation,
heapTuple, OldestXmin,
hscan->rs_cbuf))
{
case HEAPTUPLE_DEAD:
/* Definitely dead, we can ignore it */
indexIt = false;
tupleIsAlive = false;
break;
case HEAPTUPLE_LIVE:
/* Normal case, index and unique-check it */
indexIt = true;
tupleIsAlive = true;
/* Count it as live, too */
reltuples += 1;
break;
case HEAPTUPLE_RECENTLY_DEAD:
/*
* If tuple is recently deleted then we must index it
* anyway to preserve MVCC semantics. (Pre-existing
* transactions could try to use the index after we finish
* building it, and may need to see such tuples.)
*
* However, if it was HOT-updated then we must only index
* the live tuple at the end of the HOT-chain. Since this
* breaks semantics for pre-existing snapshots, mark the
* index as unusable for them.
*
* We don't count recently-dead tuples in reltuples, even
* if we index them; see heapam_scan_analyze_next_tuple().
*/
if (HeapTupleIsHotUpdated(heapTuple))
{
indexIt = false;
/* mark the index as unsafe for old snapshots */
indexInfo->ii_BrokenHotChain = true;
}
else
indexIt = true;
/* In any case, exclude the tuple from unique-checking */
tupleIsAlive = false;
break;
case HEAPTUPLE_INSERT_IN_PROGRESS:
/*
* In "anyvisible" mode, this tuple is visible and we
* don't need any further checks.
*/
if (anyvisible)
{
indexIt = true;
tupleIsAlive = true;
reltuples += 1;
break;
}
/*
* Since caller should hold ShareLock or better, normally
* the only way to see this is if it was inserted earlier
* in our own transaction. However, it can happen in
* system catalogs, since we tend to release write lock
* before commit there. Give a warning if neither case
* applies.
*/
xwait = HeapTupleHeaderGetXmin(heapTuple->t_data);
if (!TransactionIdIsCurrentTransactionId(xwait))
{
if (!is_system_catalog)
elog(WARNING, "concurrent insert in progress within table \"%s\"",
RelationGetRelationName(heapRelation));
/*
* If we are performing uniqueness checks, indexing
* such a tuple could lead to a bogus uniqueness
* failure. In that case we wait for the inserting
* transaction to finish and check again.
*/
if (checking_uniqueness)
{
/*
* Must drop the lock on the buffer before we wait
*/
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
XactLockTableWait(xwait, heapRelation,
&heapTuple->t_self,
XLTW_InsertIndexUnique);
CHECK_FOR_INTERRUPTS();
goto recheck;
}
}
else
{
/*
* For consistency with
* heapam_scan_analyze_next_tuple(), count
* HEAPTUPLE_INSERT_IN_PROGRESS tuples as live only
* when inserted by our own transaction.
*/
reltuples += 1;
}
/*
* We must index such tuples, since if the index build
* commits then they're good.
*/
indexIt = true;
tupleIsAlive = true;
break;
case HEAPTUPLE_DELETE_IN_PROGRESS:
/*
* As with INSERT_IN_PROGRESS case, this is unexpected
* unless it's our own deletion or a system catalog; but
* in anyvisible mode, this tuple is visible.
*/
if (anyvisible)
{
indexIt = true;
tupleIsAlive = false;
reltuples += 1;
break;
}
xwait = HeapTupleHeaderGetUpdateXid(heapTuple->t_data);
if (!TransactionIdIsCurrentTransactionId(xwait))
{
if (!is_system_catalog)
elog(WARNING, "concurrent delete in progress within table \"%s\"",
RelationGetRelationName(heapRelation));
/*
* If we are performing uniqueness checks, assuming
* the tuple is dead could lead to missing a
* uniqueness violation. In that case we wait for the
* deleting transaction to finish and check again.
*
* Also, if it's a HOT-updated tuple, we should not
* index it but rather the live tuple at the end of
* the HOT-chain. However, the deleting transaction
* could abort, possibly leaving this tuple as live
* after all, in which case it has to be indexed. The
* only way to know what to do is to wait for the
* deleting transaction to finish and check again.
*/
if (checking_uniqueness ||
HeapTupleIsHotUpdated(heapTuple))
{
/*
* Must drop the lock on the buffer before we wait
*/
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
XactLockTableWait(xwait, heapRelation,
&heapTuple->t_self,
XLTW_InsertIndexUnique);
CHECK_FOR_INTERRUPTS();
goto recheck;
}
/*
* Otherwise index it but don't check for uniqueness,
* the same as a RECENTLY_DEAD tuple.
*/
indexIt = true;
/*
* Count HEAPTUPLE_DELETE_IN_PROGRESS tuples as live,
* if they were not deleted by the current
* transaction. That's what
* heapam_scan_analyze_next_tuple() does, and we want
* the behavior to be consistent.
*/
reltuples += 1;
}
else if (HeapTupleIsHotUpdated(heapTuple))
{
/*
* It's a HOT-updated tuple deleted by our own xact.
* We can assume the deletion will commit (else the
* index contents don't matter), so treat the same as
* RECENTLY_DEAD HOT-updated tuples.
*/
indexIt = false;
/* mark the index as unsafe for old snapshots */
indexInfo->ii_BrokenHotChain = true;
}
else
{
/*
* It's a regular tuple deleted by our own xact. Index
* it, but don't check for uniqueness nor count in
* reltuples, the same as a RECENTLY_DEAD tuple.
*/
indexIt = true;
}
/* In any case, exclude the tuple from unique-checking */
tupleIsAlive = false;
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
indexIt = tupleIsAlive = false; /* keep compiler quiet */
break;
}
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
if (!indexIt)
continue;
}
else
{
/* heap_getnext did the time qual check */
tupleIsAlive = true;
reltuples += 1;
}
MemoryContextReset(econtext->ecxt_per_tuple_memory);
/* Set up for predicate or expression evaluation */
ExecStoreBufferHeapTuple(heapTuple, slot, hscan->rs_cbuf);
/*
* In a partial index, discard tuples that don't satisfy the
* predicate.
*/
if (predicate != NULL)
{
if (!ExecQual(predicate, econtext))
continue;
}
/*
* For the current heap tuple, extract all the attributes we use in
* this index, and note which are null. This also performs evaluation
* of any expressions needed.
*/
FormIndexDatum(indexInfo,
slot,
estate,
values,
isnull);
/*
* You'd think we should go ahead and build the index tuple here, but
* some index AMs want to do further processing on the data first. So
* pass the values[] and isnull[] arrays, instead.
*/
if (HeapTupleIsHeapOnly(heapTuple))
{
/*
* For a heap-only tuple, pretend its TID is that of the root. See
* src/backend/access/heap/README.HOT for discussion.
*/
HeapTupleData rootTuple;
OffsetNumber offnum;
rootTuple = *heapTuple;
offnum = ItemPointerGetOffsetNumber(&heapTuple->t_self);
if (!OffsetNumberIsValid(root_offsets[offnum - 1]))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
ItemPointerGetBlockNumber(&heapTuple->t_self),
offnum,
RelationGetRelationName(heapRelation))));
ItemPointerSetOffsetNumber(&rootTuple.t_self,
root_offsets[offnum - 1]);
/* Call the AM's callback routine to process the tuple */
callback(indexRelation, &rootTuple.t_self, values, isnull, tupleIsAlive,
callback_state);
}
else
{
/* Call the AM's callback routine to process the tuple */
callback(indexRelation, &heapTuple->t_self, values, isnull, tupleIsAlive,
callback_state);
}
}
/* Report scan progress one last time. */
if (progress)
{
BlockNumber blks_done;
if (hscan->rs_base.rs_parallel != NULL)
{
ParallelBlockTableScanDesc pbscan;
pbscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
blks_done = pbscan->phs_nblocks;
}
else
blks_done = hscan->rs_nblocks;
pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_DONE,
blks_done);
}
table_endscan(scan);
/* we can now forget our snapshot, if set and registered by us */
if (need_unregister_snapshot)
UnregisterSnapshot(snapshot);
ExecDropSingleTupleTableSlot(slot);
FreeExecutorState(estate);
/* These may have been pointing to the now-gone estate */
indexInfo->ii_ExpressionsState = NIL;
indexInfo->ii_PredicateState = NULL;
return reltuples;
}
static void
heapam_index_validate_scan(Relation heapRelation,
Relation indexRelation,
IndexInfo *indexInfo,
Snapshot snapshot,
ValidateIndexState *state)
{
TableScanDesc scan;
HeapScanDesc hscan;
HeapTuple heapTuple;
Datum values[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
ExprState *predicate;
TupleTableSlot *slot;
EState *estate;
ExprContext *econtext;
BlockNumber root_blkno = InvalidBlockNumber;
OffsetNumber root_offsets[MaxHeapTuplesPerPage];
bool in_index[MaxHeapTuplesPerPage];
BlockNumber previous_blkno = InvalidBlockNumber;
/* state variables for the merge */
ItemPointer indexcursor = NULL;
ItemPointerData decoded;
bool tuplesort_empty = false;
/*
* sanity checks
*/
Assert(OidIsValid(indexRelation->rd_rel->relam));
/*
* Need an EState for evaluation of index expressions and partial-index
* predicates. Also a slot to hold the current tuple.
*/
estate = CreateExecutorState();
econtext = GetPerTupleExprContext(estate);
slot = MakeSingleTupleTableSlot(RelationGetDescr(heapRelation),
&TTSOpsHeapTuple);
/* Arrange for econtext's scan tuple to be the tuple under test */
econtext->ecxt_scantuple = slot;
/* Set up execution state for predicate, if any. */
predicate = ExecPrepareQual(indexInfo->ii_Predicate, estate);
/*
* Prepare for scan of the base relation. We need just those tuples
* satisfying the passed-in reference snapshot. We must disable syncscan
* here, because it's critical that we read from block zero forward to
* match the sorted TIDs.
*/
scan = table_beginscan_strat(heapRelation, /* relation */
snapshot, /* snapshot */
0, /* number of keys */
NULL, /* scan key */
true, /* buffer access strategy OK */
false); /* syncscan not OK */
hscan = (HeapScanDesc) scan;
pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_TOTAL,
hscan->rs_nblocks);
/*
* Scan all tuples matching the snapshot.
*/
while ((heapTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
ItemPointer heapcursor = &heapTuple->t_self;
ItemPointerData rootTuple;
OffsetNumber root_offnum;
CHECK_FOR_INTERRUPTS();
state->htups += 1;
if ((previous_blkno == InvalidBlockNumber) ||
(hscan->rs_cblock != previous_blkno))
{
pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_DONE,
hscan->rs_cblock);
previous_blkno = hscan->rs_cblock;
}
/*
* As commented in table_index_build_scan, we should index heap-only
* tuples under the TIDs of their root tuples; so when we advance onto
* a new heap page, build a map of root item offsets on the page.
*
* This complicates merging against the tuplesort output: we will
* visit the live tuples in order by their offsets, but the root
* offsets that we need to compare against the index contents might be
* ordered differently. So we might have to "look back" within the
* tuplesort output, but only within the current page. We handle that
* by keeping a bool array in_index[] showing all the
* already-passed-over tuplesort output TIDs of the current page. We
* clear that array here, when advancing onto a new heap page.
*/
if (hscan->rs_cblock != root_blkno)
{
Page page = BufferGetPage(hscan->rs_cbuf);
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
heap_get_root_tuples(page, root_offsets);
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
memset(in_index, 0, sizeof(in_index));
root_blkno = hscan->rs_cblock;
}
/* Convert actual tuple TID to root TID */
rootTuple = *heapcursor;
root_offnum = ItemPointerGetOffsetNumber(heapcursor);
if (HeapTupleIsHeapOnly(heapTuple))
{
root_offnum = root_offsets[root_offnum - 1];
if (!OffsetNumberIsValid(root_offnum))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
ItemPointerGetBlockNumber(heapcursor),
ItemPointerGetOffsetNumber(heapcursor),
RelationGetRelationName(heapRelation))));
ItemPointerSetOffsetNumber(&rootTuple, root_offnum);
}
/*
* "merge" by skipping through the index tuples until we find or pass
* the current root tuple.
*/
while (!tuplesort_empty &&
(!indexcursor ||
ItemPointerCompare(indexcursor, &rootTuple) < 0))
{
Datum ts_val;
bool ts_isnull;
if (indexcursor)
{
/*
* Remember index items seen earlier on the current heap page
*/
if (ItemPointerGetBlockNumber(indexcursor) == root_blkno)
in_index[ItemPointerGetOffsetNumber(indexcursor) - 1] = true;
}
tuplesort_empty = !tuplesort_getdatum(state->tuplesort, true,
&ts_val, &ts_isnull, NULL);
Assert(tuplesort_empty || !ts_isnull);
if (!tuplesort_empty)
{
itemptr_decode(&decoded, DatumGetInt64(ts_val));
indexcursor = &decoded;
/* If int8 is pass-by-ref, free (encoded) TID Datum memory */
#ifndef USE_FLOAT8_BYVAL
pfree(DatumGetPointer(ts_val));
#endif
}
else
{
/* Be tidy */
indexcursor = NULL;
}
}
/*
* If the tuplesort has overshot *and* we didn't see a match earlier,
* then this tuple is missing from the index, so insert it.
*/
if ((tuplesort_empty ||
ItemPointerCompare(indexcursor, &rootTuple) > 0) &&
!in_index[root_offnum - 1])
{
MemoryContextReset(econtext->ecxt_per_tuple_memory);
/* Set up for predicate or expression evaluation */
ExecStoreHeapTuple(heapTuple, slot, false);
/*
* In a partial index, discard tuples that don't satisfy the
* predicate.
*/
if (predicate != NULL)
{
if (!ExecQual(predicate, econtext))
continue;
}
/*
* For the current heap tuple, extract all the attributes we use
* in this index, and note which are null. This also performs
* evaluation of any expressions needed.
*/
FormIndexDatum(indexInfo,
slot,
estate,
values,
isnull);
/*
* You'd think we should go ahead and build the index tuple here,
* but some index AMs want to do further processing on the data
* first. So pass the values[] and isnull[] arrays, instead.
*/
/*
* If the tuple is already committed dead, you might think we
* could suppress uniqueness checking, but this is no longer true
* in the presence of HOT, because the insert is actually a proxy
* for a uniqueness check on the whole HOT-chain. That is, the
* tuple we have here could be dead because it was already
* HOT-updated, and if so the updating transaction will not have
* thought it should insert index entries. The index AM will
* check the whole HOT-chain and correctly detect a conflict if
* there is one.
*/
index_insert(indexRelation,
values,
isnull,
&rootTuple,
heapRelation,
indexInfo->ii_Unique ?
UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
indexInfo);
state->tups_inserted += 1;
}
}
table_endscan(scan);
ExecDropSingleTupleTableSlot(slot);
FreeExecutorState(estate);
/* These may have been pointing to the now-gone estate */
indexInfo->ii_ExpressionsState = NIL;
indexInfo->ii_PredicateState = NULL;
}
/*
* Return the number of blocks that have been read by this scan since
* starting. This is meant for progress reporting rather than be fully
* accurate: in a parallel scan, workers can be concurrently reading blocks
* further ahead than what we report.
*/
static BlockNumber
heapam_scan_get_blocks_done(HeapScanDesc hscan)
{
ParallelBlockTableScanDesc bpscan = NULL;
BlockNumber startblock;
BlockNumber blocks_done;
if (hscan->rs_base.rs_parallel != NULL)
{
bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
startblock = bpscan->phs_startblock;
}
else
startblock = hscan->rs_startblock;
/*
* Might have wrapped around the end of the relation, if startblock was
* not zero.
*/
if (hscan->rs_cblock > startblock)
blocks_done = hscan->rs_cblock - startblock;
else
{
BlockNumber nblocks;
nblocks = bpscan != NULL ? bpscan->phs_nblocks : hscan->rs_nblocks;
blocks_done = nblocks - startblock +
hscan->rs_cblock;
}
return blocks_done;
}
/* ------------------------------------------------------------------------
* Miscellaneous callbacks for the heap AM
* ------------------------------------------------------------------------
*/
static uint64
heapam_relation_size(Relation rel, ForkNumber forkNumber)
{
uint64 nblocks = 0;
/* Open it at the smgr level if not already done */
RelationOpenSmgr(rel);
/* InvalidForkNumber indicates returning the size for all forks */
if (forkNumber == InvalidForkNumber)
{
for (int i = 0; i < MAX_FORKNUM; i++)
nblocks += smgrnblocks(rel->rd_smgr, i);
}
else
nblocks = smgrnblocks(rel->rd_smgr, forkNumber);
return nblocks * BLCKSZ;
}
/*
* Check to see whether the table needs a TOAST table. It does only if
* (1) there are any toastable attributes, and (2) the maximum length
* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
* create a toast table for something like "f1 varchar(20)".)
*/
static bool
heapam_relation_needs_toast_table(Relation rel)
{
int32 data_length = 0;
bool maxlength_unknown = false;
bool has_toastable_attrs = false;
TupleDesc tupdesc = rel->rd_att;
int32 tuple_length;
int i;
for (i = 0; i < tupdesc->natts; i++)
{
Form_pg_attribute att = TupleDescAttr(tupdesc, i);
if (att->attisdropped)
continue;
data_length = att_align_nominal(data_length, att->attalign);
if (att->attlen > 0)
{
/* Fixed-length types are never toastable */
data_length += att->attlen;
}
else
{
int32 maxlen = type_maximum_size(att->atttypid,
att->atttypmod);
if (maxlen < 0)
maxlength_unknown = true;
else
data_length += maxlen;
if (att->attstorage != 'p')
has_toastable_attrs = true;
}
}
if (!has_toastable_attrs)
return false; /* nothing to toast? */
if (maxlength_unknown)
return true; /* any unlimited-length attrs? */
tuple_length = MAXALIGN(SizeofHeapTupleHeader +
BITMAPLEN(tupdesc->natts)) +
MAXALIGN(data_length);
return (tuple_length > TOAST_TUPLE_THRESHOLD);
}
/* ------------------------------------------------------------------------
* Planner related callbacks for the heap AM
* ------------------------------------------------------------------------
*/
static void
heapam_estimate_rel_size(Relation rel, int32 *attr_widths,
BlockNumber *pages, double *tuples,
double *allvisfrac)
{
BlockNumber curpages;
BlockNumber relpages;
double reltuples;
BlockNumber relallvisible;
double density;
/* it has storage, ok to call the smgr */
curpages = RelationGetNumberOfBlocks(rel);
/* coerce values in pg_class to more desirable types */
relpages = (BlockNumber) rel->rd_rel->relpages;
reltuples = (double) rel->rd_rel->reltuples;
relallvisible = (BlockNumber) rel->rd_rel->relallvisible;
/*
* HACK: if the relation has never yet been vacuumed, use a minimum size
* estimate of 10 pages. The idea here is to avoid assuming a
* newly-created table is really small, even if it currently is, because
* that may not be true once some data gets loaded into it. Once a vacuum
* or analyze cycle has been done on it, it's more reasonable to believe
* the size is somewhat stable.
*
* (Note that this is only an issue if the plan gets cached and used again
* after the table has been filled. What we're trying to avoid is using a
* nestloop-type plan on a table that has grown substantially since the
* plan was made. Normally, autovacuum/autoanalyze will occur once enough
* inserts have happened and cause cached-plan invalidation; but that
* doesn't happen instantaneously, and it won't happen at all for cases
* such as temporary tables.)
*
* We approximate "never vacuumed" by "has relpages = 0", which means this
* will also fire on genuinely empty relations. Not great, but
* fortunately that's a seldom-seen case in the real world, and it
* shouldn't degrade the quality of the plan too much anyway to err in
* this direction.
*
* If the table has inheritance children, we don't apply this heuristic.
* Totally empty parent tables are quite common, so we should be willing
* to believe that they are empty.
*/
if (curpages < 10 &&
relpages == 0 &&
!rel->rd_rel->relhassubclass)
curpages = 10;
/* report estimated # pages */
*pages = curpages;
/* quick exit if rel is clearly empty */
if (curpages == 0)
{
*tuples = 0;
*allvisfrac = 0;
return;
}
/* estimate number of tuples from previous tuple density */
if (relpages > 0)
density = reltuples / (double) relpages;
else
{
/*
* When we have no data because the relation was truncated, estimate
* tuple width from attribute datatypes. We assume here that the
* pages are completely full, which is OK for tables (since they've
* presumably not been VACUUMed yet) but is probably an overestimate
* for indexes. Fortunately get_relation_info() can clamp the
* overestimate to the parent table's size.
*
* Note: this code intentionally disregards alignment considerations,
* because (a) that would be gilding the lily considering how crude
* the estimate is, and (b) it creates platform dependencies in the
* default plans which are kind of a headache for regression testing.
*/
int32 tuple_width;
tuple_width = get_rel_data_width(rel, attr_widths);
tuple_width += MAXALIGN(SizeofHeapTupleHeader);
tuple_width += sizeof(ItemIdData);
/* note: integer division is intentional here */
density = (BLCKSZ - SizeOfPageHeaderData) / tuple_width;
}
*tuples = rint(density * (double) curpages);
/*
* We use relallvisible as-is, rather than scaling it up like we do for
* the pages and tuples counts, on the theory that any pages added since
* the last VACUUM are most likely not marked all-visible. But costsize.c
* wants it converted to a fraction.
*/
if (relallvisible == 0 || curpages <= 0)
*allvisfrac = 0;
else if ((double) relallvisible >= curpages)
*allvisfrac = 1;
else
*allvisfrac = (double) relallvisible / curpages;
}
/* ------------------------------------------------------------------------
* Executor related callbacks for the heap AM
* ------------------------------------------------------------------------
*/
static bool
heapam_scan_bitmap_next_block(TableScanDesc scan,
TBMIterateResult *tbmres)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
BlockNumber page = tbmres->blockno;
Buffer buffer;
Snapshot snapshot;
int ntup;
hscan->rs_cindex = 0;
hscan->rs_ntuples = 0;
/*
* Ignore any claimed entries past what we think is the end of the
* relation. It may have been extended after the start of our scan (we
* only hold an AccessShareLock, and it could be inserts from this
* backend).
*/
if (page >= hscan->rs_nblocks)
return false;
/*
* Acquire pin on the target heap page, trading in any pin we held before.
*/
hscan->rs_cbuf = ReleaseAndReadBuffer(hscan->rs_cbuf,
scan->rs_rd,
page);
hscan->rs_cblock = page;
buffer = hscan->rs_cbuf;
snapshot = scan->rs_snapshot;
ntup = 0;
/*
* Prune and repair fragmentation for the whole page, if possible.
*/
heap_page_prune_opt(scan->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);
/*
* We need two separate strategies for lossy and non-lossy cases.
*/
if (tbmres->ntuples >= 0)
{
/*
* Bitmap is non-lossy, so we just look through the offsets listed in
* tbmres; but we have to follow any HOT chain starting at each such
* offset.
*/
int curslot;
for (curslot = 0; curslot < tbmres->ntuples; curslot++)
{
OffsetNumber offnum = tbmres->offsets[curslot];
ItemPointerData tid;
HeapTupleData heapTuple;
ItemPointerSet(&tid, page, offnum);
if (heap_hot_search_buffer(&tid, scan->rs_rd, buffer, snapshot,
&heapTuple, NULL, true))
hscan->rs_vistuples[ntup++] = ItemPointerGetOffsetNumber(&tid);
}
}
else
{
/*
* Bitmap is lossy, so we must examine each line pointer on the page.
* But we can ignore HOT chains, since we'll check each tuple anyway.
*/
Page dp = (Page) BufferGetPage(buffer);
OffsetNumber maxoff = PageGetMaxOffsetNumber(dp);
OffsetNumber offnum;
for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum))
{
ItemId lp;
HeapTupleData loctup;
bool valid;
lp = PageGetItemId(dp, offnum);
if (!ItemIdIsNormal(lp))
continue;
loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
loctup.t_len = ItemIdGetLength(lp);
loctup.t_tableOid = scan->rs_rd->rd_id;
ItemPointerSet(&loctup.t_self, page, offnum);
valid = HeapTupleSatisfiesVisibility(scan->rs_rd, &loctup, snapshot, buffer);
if (valid)
{
hscan->rs_vistuples[ntup++] = offnum;
PredicateLockTuple(scan->rs_rd, &loctup, snapshot);
}
CheckForSerializableConflictOut(valid, scan->rs_rd, &loctup,
buffer, snapshot);
}
}
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
Assert(ntup <= MaxHeapTuplesPerPage);
hscan->rs_ntuples = ntup;
return ntup > 0;
}
static bool
heapam_scan_bitmap_next_tuple(TableScanDesc scan,
TBMIterateResult *tbmres,
TupleTableSlot *slot)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
OffsetNumber targoffset;
Page dp;
ItemId lp;
/*
* Out of range? If so, nothing more to look at on this page
*/
if (hscan->rs_cindex < 0 || hscan->rs_cindex >= hscan->rs_ntuples)
return false;
targoffset = hscan->rs_vistuples[hscan->rs_cindex];
dp = (Page) BufferGetPage(hscan->rs_cbuf);
lp = PageGetItemId(dp, targoffset);
Assert(ItemIdIsNormal(lp));
hscan->rs_ctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
hscan->rs_ctup.t_len = ItemIdGetLength(lp);
hscan->rs_ctup.t_tableOid = scan->rs_rd->rd_id;
ItemPointerSet(&hscan->rs_ctup.t_self, hscan->rs_cblock, targoffset);
pgstat_count_heap_fetch(scan->rs_rd);
/*
* Set up the result slot to point to this tuple. Note that the slot
* acquires a pin on the buffer.
*/
ExecStoreBufferHeapTuple(&hscan->rs_ctup,
slot,
hscan->rs_cbuf);
hscan->rs_cindex++;
return true;
}
static bool
heapam_scan_sample_next_block(TableScanDesc scan, SampleScanState *scanstate)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
TsmRoutine *tsm = scanstate->tsmroutine;
BlockNumber blockno;
/* return false immediately if relation is empty */
if (hscan->rs_nblocks == 0)
return false;
if (tsm->NextSampleBlock)
{
blockno = tsm->NextSampleBlock(scanstate, hscan->rs_nblocks);
hscan->rs_cblock = blockno;
}
else
{
/* scanning table sequentially */
if (hscan->rs_cblock == InvalidBlockNumber)
{
Assert(!hscan->rs_inited);
blockno = hscan->rs_startblock;
}
else
{
Assert(hscan->rs_inited);
blockno = hscan->rs_cblock + 1;
if (blockno >= hscan->rs_nblocks)
{
/* wrap to beginning of rel, might not have started at 0 */
blockno = 0;
}
/*
* Report our new scan position for synchronization purposes.
*
* 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_flags & SO_ALLOW_SYNC)
ss_report_location(scan->rs_rd, blockno);
if (blockno == hscan->rs_startblock)
{
blockno = InvalidBlockNumber;
}
}
}
if (!BlockNumberIsValid(blockno))
{
if (BufferIsValid(hscan->rs_cbuf))
ReleaseBuffer(hscan->rs_cbuf);
hscan->rs_cbuf = InvalidBuffer;
hscan->rs_cblock = InvalidBlockNumber;
hscan->rs_inited = false;
return false;
}
heapgetpage(scan, blockno);
hscan->rs_inited = true;
return true;
}
static bool
heapam_scan_sample_next_tuple(TableScanDesc scan, SampleScanState *scanstate,
TupleTableSlot *slot)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
TsmRoutine *tsm = scanstate->tsmroutine;
BlockNumber blockno = hscan->rs_cblock;
bool pagemode = (scan->rs_flags & SO_ALLOW_PAGEMODE) != 0;
Page page;
bool all_visible;
OffsetNumber maxoffset;
/*
* When not using pagemode, we must lock the buffer during tuple
* visibility checks.
*/
if (!pagemode)
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
page = (Page) BufferGetPage(hscan->rs_cbuf);
all_visible = PageIsAllVisible(page) &&
!scan->rs_snapshot->takenDuringRecovery;
maxoffset = PageGetMaxOffsetNumber(page);
for (;;)
{
OffsetNumber tupoffset;
CHECK_FOR_INTERRUPTS();
/* Ask the tablesample method which tuples to check on this page. */
tupoffset = tsm->NextSampleTuple(scanstate,
blockno,
maxoffset);
if (OffsetNumberIsValid(tupoffset))
{
ItemId itemid;
bool visible;
HeapTuple tuple = &(hscan->rs_ctup);
/* Skip invalid tuple pointers. */
itemid = PageGetItemId(page, tupoffset);
if (!ItemIdIsNormal(itemid))
continue;
tuple->t_data = (HeapTupleHeader) PageGetItem(page, itemid);
tuple->t_len = ItemIdGetLength(itemid);
ItemPointerSet(&(tuple->t_self), blockno, tupoffset);
if (all_visible)
visible = true;
else
visible = SampleHeapTupleVisible(scan, hscan->rs_cbuf,
tuple, tupoffset);
/* in pagemode, heapgetpage did this for us */
if (!pagemode)
CheckForSerializableConflictOut(visible, scan->rs_rd, tuple,
hscan->rs_cbuf, scan->rs_snapshot);
/* Try next tuple from same page. */
if (!visible)
continue;
/* Found visible tuple, return it. */
if (!pagemode)
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
ExecStoreBufferHeapTuple(tuple, slot, hscan->rs_cbuf);
/* Count successfully-fetched tuples as heap fetches */
pgstat_count_heap_getnext(scan->rs_rd);
return true;
}
else
{
/*
* If we get here, it means we've exhausted the items on this page
* and it's time to move to the next.
*/
if (!pagemode)
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
ExecClearTuple(slot);
return false;
}
}
Assert(0);
}
/* ----------------------------------------------------------------------------
* Helper functions for the above.
* ----------------------------------------------------------------------------
*/
/*
* Reconstruct and rewrite the given tuple
*
* We cannot simply copy the tuple as-is, for several reasons:
*
* 1. We'd like to squeeze out the values of any dropped columns, both
* to save space and to ensure we have no corner-case failures. (It's
* possible for example that the new table hasn't got a TOAST table
* and so is unable to store any large values of dropped cols.)
*
* 2. The tuple might not even be legal for the new table; this is
* currently only known to happen as an after-effect of ALTER TABLE
* SET WITHOUT OIDS.
*
* So, we must reconstruct the tuple from component Datums.
*/
static void
reform_and_rewrite_tuple(HeapTuple tuple,
Relation OldHeap, Relation NewHeap,
Datum *values, bool *isnull, RewriteState rwstate)
{
TupleDesc oldTupDesc = RelationGetDescr(OldHeap);
TupleDesc newTupDesc = RelationGetDescr(NewHeap);
HeapTuple copiedTuple;
int i;
heap_deform_tuple(tuple, oldTupDesc, values, isnull);
/* Be sure to null out any dropped columns */
for (i = 0; i < newTupDesc->natts; i++)
{
if (TupleDescAttr(newTupDesc, i)->attisdropped)
isnull[i] = true;
}
copiedTuple = heap_form_tuple(newTupDesc, values, isnull);
/* The heap rewrite module does the rest */
rewrite_heap_tuple(rwstate, tuple, copiedTuple);
heap_freetuple(copiedTuple);
}
/*
* Check visibility of the tuple.
*/
static bool
SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer,
HeapTuple tuple,
OffsetNumber tupoffset)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
if (scan->rs_flags & SO_ALLOW_PAGEMODE)
{
/*
* In pageatatime mode, heapgetpage() already did visibility checks,
* so just look at the info it left in rs_vistuples[].
*
* We use a binary search over the known-sorted array. Note: we could
* save some effort if we insisted that NextSampleTuple select tuples
* in increasing order, but it's not clear that there would be enough
* gain to justify the restriction.
*/
int start = 0,
end = hscan->rs_ntuples - 1;
while (start <= end)
{
int mid = (start + end) / 2;
OffsetNumber curoffset = hscan->rs_vistuples[mid];
if (tupoffset == curoffset)
return true;
else if (tupoffset < curoffset)
end = mid - 1;
else
start = mid + 1;
}
return false;
}
else
{
/* Otherwise, we have to check the tuple individually. */
return HeapTupleSatisfiesVisibility(scan->rs_rd,
tuple, scan->rs_snapshot,
buffer);
}
}
/* ------------------------------------------------------------------------
* Definition of the heap table access method.
* ------------------------------------------------------------------------
*/
static const TableAmRoutine heapam_methods = {
.type = T_TableAmRoutine,
.slot_callbacks = heapam_slot_callbacks,
.scan_begin = heap_beginscan,
.scan_end = heap_endscan,
.scan_rescan = heap_rescan,
.scan_getnextslot = heap_getnextslot,
.parallelscan_estimate = table_block_parallelscan_estimate,
.parallelscan_initialize = table_block_parallelscan_initialize,
.parallelscan_reinitialize = table_block_parallelscan_reinitialize,
.index_fetch_begin = heapam_index_fetch_begin,
.index_fetch_reset = heapam_index_fetch_reset,
.index_fetch_end = heapam_index_fetch_end,
.index_fetch_tuple = heapam_index_fetch_tuple,
.tuple_insert = heapam_tuple_insert,
.tuple_insert_speculative = heapam_tuple_insert_speculative,
.tuple_complete_speculative = heapam_tuple_complete_speculative,
.multi_insert = heap_multi_insert,
.tuple_delete = heapam_tuple_delete,
.tuple_update = heapam_tuple_update,
.tuple_lock = heapam_tuple_lock,
.finish_bulk_insert = heapam_finish_bulk_insert,
.tuple_fetch_row_version = heapam_fetch_row_version,
.tuple_get_latest_tid = heap_get_latest_tid,
.tuple_tid_valid = heapam_tuple_tid_valid,
.tuple_satisfies_snapshot = heapam_tuple_satisfies_snapshot,
.compute_xid_horizon_for_tuples = heap_compute_xid_horizon_for_tuples,
.relation_set_new_filenode = heapam_relation_set_new_filenode,
.relation_nontransactional_truncate = heapam_relation_nontransactional_truncate,
.relation_copy_data = heapam_relation_copy_data,
.relation_copy_for_cluster = heapam_relation_copy_for_cluster,
.relation_vacuum = lazy_vacuum_rel_heap,
.scan_analyze_next_block = heapam_scan_analyze_next_block,
.scan_analyze_next_tuple = heapam_scan_analyze_next_tuple,
.index_build_range_scan = heapam_index_build_range_scan,
.index_validate_scan = heapam_index_validate_scan,
.relation_size = heapam_relation_size,
.relation_needs_toast_table = heapam_relation_needs_toast_table,
.relation_estimate_size = heapam_estimate_rel_size,
.scan_bitmap_next_block = heapam_scan_bitmap_next_block,
.scan_bitmap_next_tuple = heapam_scan_bitmap_next_tuple,
.scan_sample_next_block = heapam_scan_sample_next_block,
.scan_sample_next_tuple = heapam_scan_sample_next_tuple
};
const TableAmRoutine *
GetHeapamTableAmRoutine(void)
{
return &heapam_methods;
}
Datum
heap_tableam_handler(PG_FUNCTION_ARGS)
{
PG_RETURN_POINTER(&heapam_methods);
}
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