greenplumn indexam 源码
greenplumn indexam 代码
文件路径：/src/backend/access/index/indexam.c
/*-------------------------------------------------------------------------
*
* indexam.c
* general index access method routines
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/access/index/indexam.c
*
* INTERFACE ROUTINES
* index_open - open an index relation by relation OID
* index_close - close an index relation
* index_beginscan - start a scan of an index with amgettuple
* index_beginscan_bitmap - start a scan of an index with amgetbitmap
* index_rescan - restart a scan of an index
* index_endscan - end a scan
* index_insert - insert an index tuple into a relation
* index_markpos - mark a scan position
* index_restrpos - restore a scan position
* index_parallelscan_estimate - estimate shared memory for parallel scan
* index_parallelscan_initialize - initialize parallel scan
* index_parallelrescan - (re)start a parallel scan of an index
* index_beginscan_parallel - join parallel index scan
* index_getnext_tid - get the next TID from a scan
* index_fetch_heap - get the scan's next heap tuple
* index_getnext_slot - get the next tuple from a scan
* index_getbitmap - get all tuples from a scan
* index_bulk_delete - bulk deletion of index tuples
* index_vacuum_cleanup - post-deletion cleanup of an index
* index_can_return - does index support index-only scans?
* index_getprocid - get a support procedure OID
* index_getprocinfo - get a support procedure's lookup info
*
* NOTES
* This file contains the index_ routines which used
* to be a scattered collection of stuff in access/genam.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/amapi.h"
#include "access/heapam.h"
#include "access/relscan.h"
#include "access/tableam.h"
#include "access/transam.h"
#include "access/xlog.h"
#include "catalog/index.h"
#include "catalog/pg_type.h"
#include "pgstat.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/predicate.h"
#include "utils/snapmgr.h"
/* ----------------------------------------------------------------
* macros used in index_ routines
*
* Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
* to check that we don't try to scan or do retail insertions into an index
* that is currently being rebuilt or pending rebuild. This helps to catch
* things that don't work when reindexing system catalogs. The assertion
* doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
* when calling the index AM's ambuild routine, and there is no reason for
* ambuild to call its subsidiary routines through this file.
* ----------------------------------------------------------------
*/
#define RELATION_CHECKS \
( \
AssertMacro(RelationIsValid(indexRelation)), \
AssertMacro(PointerIsValid(indexRelation->rd_indam)), \
AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
)
#define SCAN_CHECKS \
( \
AssertMacro(IndexScanIsValid(scan)), \
AssertMacro(RelationIsValid(scan->indexRelation)), \
AssertMacro(PointerIsValid(scan->indexRelation->rd_indam)) \
)
#define CHECK_REL_PROCEDURE(pname) \
do { \
if (indexRelation->rd_indam->pname == NULL) \
elog(ERROR, "function %s is not defined for index %s", \
CppAsString(pname), RelationGetRelationName(indexRelation)); \
} while(0)
#define CHECK_SCAN_PROCEDURE(pname) \
do { \
if (scan->indexRelation->rd_indam->pname == NULL) \
elog(ERROR, "function %s is not defined for index %s", \
CppAsString(pname), RelationGetRelationName(scan->indexRelation)); \
} while(0)
static IndexScanDesc index_beginscan_internal(Relation indexRelation,
int nkeys, int norderbys, Snapshot snapshot,
ParallelIndexScanDesc pscan, bool temp_snap);
/* ----------------------------------------------------------------
* index_ interface functions
* ----------------------------------------------------------------
*/
/* ----------------
* index_open - open an index relation by relation OID
*
* If lockmode is not "NoLock", the specified kind of lock is
* obtained on the index. (Generally, NoLock should only be
* used if the caller knows it has some appropriate lock on the
* index already.)
*
* An error is raised if the index does not exist.
*
* This is a convenience routine adapted for indexscan use.
* Some callers may prefer to use relation_open directly.
* ----------------
*/
Relation
index_open(Oid relationId, LOCKMODE lockmode)
{
Relation r;
r = relation_open(relationId, lockmode);
if (r->rd_rel->relkind != RELKIND_INDEX &&
r->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("\"%s\" is not an index",
RelationGetRelationName(r))));
return r;
}
/* ----------------
* index_close - close an index relation
*
* If lockmode is not "NoLock", we then release the specified lock.
*
* Note that it is often sensible to hold a lock beyond index_close;
* in that case, the lock is released automatically at xact end.
* ----------------
*/
void
index_close(Relation relation, LOCKMODE lockmode)
{
LockRelId relid = relation->rd_lockInfo.lockRelId;
Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
/* The relcache does the real work... */
RelationClose(relation);
if (lockmode != NoLock)
UnlockRelationId(&relid, lockmode);
}
/* ----------------
* index_insert - insert an index tuple into a relation
* ----------------
*/
bool
index_insert(Relation indexRelation,
Datum *values,
bool *isnull,
ItemPointer heap_t_ctid,
Relation heapRelation,
IndexUniqueCheck checkUnique,
IndexInfo *indexInfo)
{
RELATION_CHECKS;
CHECK_REL_PROCEDURE(aminsert);
if (!(indexRelation->rd_indam->ampredlocks))
CheckForSerializableConflictIn(indexRelation,
(HeapTuple) NULL,
InvalidBuffer);
return indexRelation->rd_indam->aminsert(indexRelation, values, isnull,
heap_t_ctid, heapRelation,
checkUnique, indexInfo);
}
/*
* index_beginscan - start a scan of an index with amgettuple
*
* Caller must be holding suitable locks on the heap and the index.
*/
IndexScanDesc
index_beginscan(Relation heapRelation,
Relation indexRelation,
Snapshot snapshot,
int nkeys, int norderbys)
{
IndexScanDesc scan;
scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot, NULL, false);
/*
* Save additional parameters into the scandesc. Everything else was set
* up by RelationGetIndexScan.
*/
scan->heapRelation = heapRelation;
scan->xs_snapshot = snapshot;
/* prepare to fetch index matches from table */
scan->xs_heapfetch = table_index_fetch_begin(heapRelation);
return scan;
}
/*
* index_beginscan_bitmap - start a scan of an index with amgetbitmap
*
* As above, caller had better be holding some lock on the parent heap
* relation, even though it's not explicitly mentioned here.
*/
IndexScanDesc
index_beginscan_bitmap(Relation indexRelation,
Snapshot snapshot,
int nkeys)
{
IndexScanDesc scan;
scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot, NULL, false);
/*
* Save additional parameters into the scandesc. Everything else was set
* up by RelationGetIndexScan.
*/
scan->xs_snapshot = snapshot;
return scan;
}
/*
* index_beginscan_internal --- common code for index_beginscan variants
*/
static IndexScanDesc
index_beginscan_internal(Relation indexRelation,
int nkeys, int norderbys, Snapshot snapshot,
ParallelIndexScanDesc pscan, bool temp_snap)
{
IndexScanDesc scan;
RELATION_CHECKS;
CHECK_REL_PROCEDURE(ambeginscan);
if (!(indexRelation->rd_indam->ampredlocks))
PredicateLockRelation(indexRelation, snapshot);
/*
* We hold a reference count to the relcache entry throughout the scan.
*/
RelationIncrementReferenceCount(indexRelation);
/*
* Tell the AM to open a scan.
*/
scan = indexRelation->rd_indam->ambeginscan(indexRelation, nkeys,
norderbys);
/* Initialize information for parallel scan. */
scan->parallel_scan = pscan;
scan->xs_temp_snap = temp_snap;
return scan;
}
/* ----------------
* index_rescan - (re)start a scan of an index
*
* During a restart, the caller may specify a new set of scankeys and/or
* orderbykeys; but the number of keys cannot differ from what index_beginscan
* was told. (Later we might relax that to "must not exceed", but currently
* the index AMs tend to assume that scan->numberOfKeys is what to believe.)
* To restart the scan without changing keys, pass NULL for the key arrays.
* (Of course, keys *must* be passed on the first call, unless
* scan->numberOfKeys is zero.)
* ----------------
*/
void
index_rescan(IndexScanDesc scan,
ScanKey keys, int nkeys,
ScanKey orderbys, int norderbys)
{
SCAN_CHECKS;
CHECK_SCAN_PROCEDURE(amrescan);
Assert(nkeys == scan->numberOfKeys);
Assert(norderbys == scan->numberOfOrderBys);
/* Release resources (like buffer pins) from table accesses */
if (scan->xs_heapfetch)
table_index_fetch_reset(scan->xs_heapfetch);
scan->kill_prior_tuple = false; /* for safety */
scan->xs_heap_continue = false;
scan->indexRelation->rd_indam->amrescan(scan, keys, nkeys,
orderbys, norderbys);
}
/* ----------------
* index_endscan - end a scan
* ----------------
*/
void
index_endscan(IndexScanDesc scan)
{
SCAN_CHECKS;
CHECK_SCAN_PROCEDURE(amendscan);
/* Release resources (like buffer pins) from table accesses */
if (scan->xs_heapfetch)
{
table_index_fetch_end(scan->xs_heapfetch);
scan->xs_heapfetch = NULL;
}
/* End the AM's scan */
scan->indexRelation->rd_indam->amendscan(scan);
/* Release index refcount acquired by index_beginscan */
RelationDecrementReferenceCount(scan->indexRelation);
if (scan->xs_temp_snap)
UnregisterSnapshot(scan->xs_snapshot);
/* Release the scan data structure itself */
IndexScanEnd(scan);
}
/* ----------------
* index_markpos - mark a scan position
* ----------------
*/
void
index_markpos(IndexScanDesc scan)
{
SCAN_CHECKS;
CHECK_SCAN_PROCEDURE(ammarkpos);
scan->indexRelation->rd_indam->ammarkpos(scan);
}
/* ----------------
* index_restrpos - restore a scan position
*
* NOTE: this only restores the internal scan state of the index AM. See
* comments for ExecRestrPos().
*
* NOTE: For heap, in the presence of HOT chains, mark/restore only works
* correctly if the scan's snapshot is MVCC-safe; that ensures that there's at
* most one returnable tuple in each HOT chain, and so restoring the prior
* state at the granularity of the index AM is sufficient. Since the only
* current user of mark/restore functionality is nodeMergejoin.c, this
* effectively means that merge-join plans only work for MVCC snapshots. This
* could be fixed if necessary, but for now it seems unimportant.
* ----------------
*/
void
index_restrpos(IndexScanDesc scan)
{
Assert(IsMVCCSnapshot(scan->xs_snapshot));
SCAN_CHECKS;
CHECK_SCAN_PROCEDURE(amrestrpos);
/* release resources (like buffer pins) from table accesses */
if (scan->xs_heapfetch)
table_index_fetch_reset(scan->xs_heapfetch);
scan->kill_prior_tuple = false; /* for safety */
scan->xs_heap_continue = false;
scan->indexRelation->rd_indam->amrestrpos(scan);
}
/*
* index_parallelscan_estimate - estimate shared memory for parallel scan
*
* Currently, we don't pass any information to the AM-specific estimator,
* so it can probably only return a constant. In the future, we might need
* to pass more information.
*/
Size
index_parallelscan_estimate(Relation indexRelation, Snapshot snapshot)
{
Size nbytes;
RELATION_CHECKS;
nbytes = offsetof(ParallelIndexScanDescData, ps_snapshot_data);
nbytes = add_size(nbytes, EstimateSnapshotSpace(snapshot));
nbytes = MAXALIGN(nbytes);
/*
* If amestimateparallelscan is not provided, assume there is no
* AM-specific data needed. (It's hard to believe that could work, but
* it's easy enough to cater to it here.)
*/
if (indexRelation->rd_indam->amestimateparallelscan != NULL)
nbytes = add_size(nbytes,
indexRelation->rd_indam->amestimateparallelscan());
return nbytes;
}
/*
* index_parallelscan_initialize - initialize parallel scan
*
* We initialize both the ParallelIndexScanDesc proper and the AM-specific
* information which follows it.
*
* This function calls access method specific initialization routine to
* initialize am specific information. Call this just once in the leader
* process; then, individual workers attach via index_beginscan_parallel.
*/
void
index_parallelscan_initialize(Relation heapRelation, Relation indexRelation,
Snapshot snapshot, ParallelIndexScanDesc target)
{
Size offset;
RELATION_CHECKS;
offset = add_size(offsetof(ParallelIndexScanDescData, ps_snapshot_data),
EstimateSnapshotSpace(snapshot));
offset = MAXALIGN(offset);
target->ps_relid = RelationGetRelid(heapRelation);
target->ps_indexid = RelationGetRelid(indexRelation);
target->ps_offset = offset;
SerializeSnapshot(snapshot, target->ps_snapshot_data);
/* aminitparallelscan is optional; assume no-op if not provided by AM */
if (indexRelation->rd_indam->aminitparallelscan != NULL)
{
void *amtarget;
amtarget = OffsetToPointer(target, offset);
indexRelation->rd_indam->aminitparallelscan(amtarget);
}
}
/* ----------------
* index_parallelrescan - (re)start a parallel scan of an index
* ----------------
*/
void
index_parallelrescan(IndexScanDesc scan)
{
SCAN_CHECKS;
if (scan->xs_heapfetch)
table_index_fetch_reset(scan->xs_heapfetch);
/* amparallelrescan is optional; assume no-op if not provided by AM */
if (scan->indexRelation->rd_indam->amparallelrescan != NULL)
scan->indexRelation->rd_indam->amparallelrescan(scan);
}
/*
* index_beginscan_parallel - join parallel index scan
*
* Caller must be holding suitable locks on the heap and the index.
*/
IndexScanDesc
index_beginscan_parallel(Relation heaprel, Relation indexrel, int nkeys,
int norderbys, ParallelIndexScanDesc pscan)
{
Snapshot snapshot;
IndexScanDesc scan;
Assert(RelationGetRelid(heaprel) == pscan->ps_relid);
snapshot = RestoreSnapshot(pscan->ps_snapshot_data);
RegisterSnapshot(snapshot);
scan = index_beginscan_internal(indexrel, nkeys, norderbys, snapshot,
pscan, true);
/*
* Save additional parameters into the scandesc. Everything else was set
* up by index_beginscan_internal.
*/
scan->heapRelation = heaprel;
scan->xs_snapshot = snapshot;
/* prepare to fetch index matches from table */
scan->xs_heapfetch = table_index_fetch_begin(heaprel);
return scan;
}
/* ----------------
* index_getnext_tid - get the next TID from a scan
*
* The result is the next TID satisfying the scan keys,
* or NULL if no more matching tuples exist.
* ----------------
*/
ItemPointer
index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
{
bool found;
SCAN_CHECKS;
CHECK_SCAN_PROCEDURE(amgettuple);
Assert(TransactionIdIsValid(RecentGlobalXmin));
/*
* The AM's amgettuple proc finds the next index entry matching the scan
* keys, and puts the TID into scan->xs_heaptid. It should also set
* scan->xs_recheck and possibly scan->xs_itup/scan->xs_hitup, though we
* pay no attention to those fields here.
*/
found = scan->indexRelation->rd_indam->amgettuple(scan, direction);
/* Reset kill flag immediately for safety */
scan->kill_prior_tuple = false;
scan->xs_heap_continue = false;
/* If we're out of index entries, we're done */
if (!found)
{
/* release resources (like buffer pins) from table accesses */
if (scan->xs_heapfetch)
table_index_fetch_reset(scan->xs_heapfetch);
return NULL;
}
Assert(ItemPointerIsValid(&scan->xs_heaptid));
pgstat_count_index_tuples(scan->indexRelation, 1);
/* Return the TID of the tuple we found. */
return &scan->xs_heaptid;
}
/* ----------------
* index_fetch_heap - get the scan's next heap tuple
*
* The result is a visible heap tuple associated with the index TID most
* recently fetched by index_getnext_tid, or NULL if no more matching tuples
* exist. (There can be more than one matching tuple because of HOT chains,
* although when using an MVCC snapshot it should be impossible for more than
* one such tuple to exist.)
*
* On success, the buffer containing the heap tup is pinned (the pin will be
* dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
* call).
*
* Note: caller must check scan->xs_recheck, and perform rechecking of the
* scan keys if required. We do not do that here because we don't have
* enough information to do it efficiently in the general case.
* ----------------
*/
bool
index_fetch_heap(IndexScanDesc scan, TupleTableSlot *slot)
{
bool all_dead = false;
bool found;
found = table_index_fetch_tuple(scan->xs_heapfetch, &scan->xs_heaptid,
scan->xs_snapshot, slot,
&scan->xs_heap_continue, &all_dead);
if (found)
pgstat_count_heap_fetch(scan->indexRelation);
/*
* If we scanned a whole HOT chain and found only dead tuples, tell index
* AM to kill its entry for that TID (this will take effect in the next
* amgettuple call, in index_getnext_tid). We do not do this when in
* recovery because it may violate MVCC to do so. See comments in
* RelationGetIndexScan().
*/
if (!scan->xactStartedInRecovery)
scan->kill_prior_tuple = all_dead;
return found;
}
/* ----------------
* index_getnext_slot - get the next tuple from a scan
*
* The result is true if a tuple satisfying the scan keys and the snapshot was
* found, false otherwise. The tuple is stored in the specified slot.
*
* On success, resources (like buffer pins) are likely to be held, and will be
* dropped by a future index_getnext_tid, index_fetch_heap or index_endscan
* call).
*
* Note: caller must check scan->xs_recheck, and perform rechecking of the
* scan keys if required. We do not do that here because we don't have
* enough information to do it efficiently in the general case.
* ----------------
*/
bool
index_getnext_slot(IndexScanDesc scan, ScanDirection direction, TupleTableSlot *slot)
{
for (;;)
{
if (!scan->xs_heap_continue)
{
ItemPointer tid;
/* Time to fetch the next TID from the index */
tid = index_getnext_tid(scan, direction);
/* If we're out of index entries, we're done */
if (tid == NULL)
break;
Assert(ItemPointerEquals(tid, &scan->xs_heaptid));
}
/*
* Fetch the next (or only) visible heap tuple for this index entry.
* If we don't find anything, loop around and grab the next TID from
* the index.
*/
Assert(ItemPointerIsValid(&scan->xs_heaptid));
if (index_fetch_heap(scan, slot))
return true;
}
return false;
}
/* ----------------
* index_getbitmap - get all tuples at once from an index scan
*
* it invokes am's getmulti function to get a bitmap. If am is an on-disk
* bitmap index access method (see bitmap.h), then a StreamBitmap is
* returned; a TIDBitmap otherwise. Note that an index am's getmulti
* function can assume that the bitmap that it's given as argument is of
* the same type as what the function constructs itself.
*
* GPDB: Since GPDB also support StreamBitmap node in bitmap index.
* So normally we need to create specific bitmap node in the amgetbitmap AM.
* This makes the function different from upstream.
* ----------------
*/
int64
index_getbitmap(IndexScanDesc scan, Node **bitmapP)
{
int64 ntids;
SCAN_CHECKS;
CHECK_SCAN_PROCEDURE(amgetbitmap);
/* just make sure this is false... */
scan->kill_prior_tuple = false;
/*
* have the am's getbitmap proc do all the work.
*/
ntids = scan->indexRelation->rd_indam->amgetbitmap(scan, bitmapP);
pgstat_count_index_tuples(scan->indexRelation, ntids);
return ntids;
}
/* ----------------
* index_bulk_delete - do mass deletion of index entries
*
* callback routine tells whether a given main-heap tuple is
* to be deleted
*
* return value is an optional palloc'd struct of statistics
* ----------------
*/
IndexBulkDeleteResult *
index_bulk_delete(IndexVacuumInfo *info,
IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback,
void *callback_state)
{
Relation indexRelation = info->index;
RELATION_CHECKS;
CHECK_REL_PROCEDURE(ambulkdelete);
return indexRelation->rd_indam->ambulkdelete(info, stats,
callback, callback_state);
}
/* ----------------
* index_vacuum_cleanup - do post-deletion cleanup of an index
*
* return value is an optional palloc'd struct of statistics
* ----------------
*/
IndexBulkDeleteResult *
index_vacuum_cleanup(IndexVacuumInfo *info,
IndexBulkDeleteResult *stats)
{
Relation indexRelation = info->index;
RELATION_CHECKS;
CHECK_REL_PROCEDURE(amvacuumcleanup);
return indexRelation->rd_indam->amvacuumcleanup(info, stats);
}
/* ----------------
* index_can_return
*
* Does the index access method support index-only scans for the given
* column?
* ----------------
*/
bool
index_can_return(Relation indexRelation, int attno)
{
RELATION_CHECKS;
/* amcanreturn is optional; assume false if not provided by AM */
if (indexRelation->rd_indam->amcanreturn == NULL)
return false;
return indexRelation->rd_indam->amcanreturn(indexRelation, attno);
}
/* ----------------
* index_getprocid
*
* Index access methods typically require support routines that are
* not directly the implementation of any WHERE-clause query operator
* and so cannot be kept in pg_amop. Instead, such routines are kept
* in pg_amproc. These registered procedure OIDs are assigned numbers
* according to a convention established by the access method.
* The general index code doesn't know anything about the routines
* involved; it just builds an ordered list of them for
* each attribute on which an index is defined.
*
* As of Postgres 8.3, support routines within an operator family
* are further subdivided by the "left type" and "right type" of the
* query operator(s) that they support. The "default" functions for a
* particular indexed attribute are those with both types equal to
* the index opclass' opcintype (note that this is subtly different
* from the indexed attribute's own type: it may be a binary-compatible
* type instead). Only the default functions are stored in relcache
* entries --- access methods can use the syscache to look up non-default
* functions.
*
* This routine returns the requested default procedure OID for a
* particular indexed attribute.
* ----------------
*/
RegProcedure
index_getprocid(Relation irel,
AttrNumber attnum,
uint16 procnum)
{
RegProcedure *loc;
int nproc;
int procindex;
nproc = irel->rd_indam->amsupport;
Assert(procnum > 0 && procnum <= (uint16) nproc);
procindex = (nproc * (attnum - 1)) + (procnum - 1);
loc = irel->rd_support;
Assert(loc != NULL);
return loc[procindex];
}
/* ----------------
* index_getprocinfo
*
* This routine allows index AMs to keep fmgr lookup info for
* support procs in the relcache. As above, only the "default"
* functions for any particular indexed attribute are cached.
*
* Note: the return value points into cached data that will be lost during
* any relcache rebuild! Therefore, either use the callinfo right away,
* or save it only after having acquired some type of lock on the index rel.
* ----------------
*/
FmgrInfo *
index_getprocinfo(Relation irel,
AttrNumber attnum,
uint16 procnum)
{
FmgrInfo *locinfo;
int nproc;
int procindex;
nproc = irel->rd_indam->amsupport;
Assert(procnum > 0 && procnum <= (uint16) nproc);
procindex = (nproc * (attnum - 1)) + (procnum - 1);
locinfo = irel->rd_supportinfo;
Assert(locinfo != NULL);
locinfo += procindex;
/* Initialize the lookup info if first time through */
if (locinfo->fn_oid == InvalidOid)
{
RegProcedure *loc = irel->rd_support;
RegProcedure procId;
Assert(loc != NULL);
procId = loc[procindex];
/*
* Complain if function was not found during IndexSupportInitialize.
* This should not happen unless the system tables contain bogus
* entries for the index opclass. (If an AM wants to allow a support
* function to be optional, it can use index_getprocid.)
*/
if (!RegProcedureIsValid(procId))
elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
procnum, attnum, RelationGetRelationName(irel));
fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
}
return locinfo;
}
/* ----------------
* index_store_float8_orderby_distances
*
* Convert AM distance function's results (that can be inexact)
* to ORDER BY types and save them into xs_orderbyvals/xs_orderbynulls
* for a possible recheck.
* ----------------
*/
void
index_store_float8_orderby_distances(IndexScanDesc scan, Oid *orderByTypes,
double *distanceValues,
bool *distanceNulls, bool recheckOrderBy)
{
int i;
scan->xs_recheckorderby = recheckOrderBy;
if (!distanceValues)
{
Assert(!scan->xs_recheckorderby);
for (i = 0; i < scan->numberOfOrderBys; i++)
{
scan->xs_orderbyvals[i] = (Datum) 0;
scan->xs_orderbynulls[i] = true;
}
return;
}
for (i = 0; i < scan->numberOfOrderBys; i++)
{
if (distanceNulls && distanceNulls[i])
{
scan->xs_orderbyvals[i] = (Datum) 0;
scan->xs_orderbynulls[i] = true;
}
if (orderByTypes[i] == FLOAT8OID)
{
#ifndef USE_FLOAT8_BYVAL
/* must free any old value to avoid memory leakage */
if (!scan->xs_orderbynulls[i])
pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
#endif
scan->xs_orderbyvals[i] = Float8GetDatum(distanceValues[i]);
scan->xs_orderbynulls[i] = false;
}
else if (orderByTypes[i] == FLOAT4OID)
{
/* convert distance function's result to ORDER BY type */
#ifndef USE_FLOAT4_BYVAL
/* must free any old value to avoid memory leakage */
if (!scan->xs_orderbynulls[i])
pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
#endif
scan->xs_orderbyvals[i] = Float4GetDatum((float4) distanceValues[i]);
scan->xs_orderbynulls[i] = false;
}
else
{
/*
* If the ordering operator's return value is anything else, we
* don't know how to convert the float8 bound calculated by the
* distance function to that. The executor won't actually need
* the order by values we return here, if there are no lossy
* results, so only insist on converting if the *recheck flag is
* set.
*/
if (scan->xs_recheckorderby)
elog(ERROR, "ORDER BY operator must return float8 or float4 if the distance function is lossy");
scan->xs_orderbynulls[i] = true;
}
}
}
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