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Use an indexscan not a heapscan to search pg_index in get_pkey_attnames.

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Noted while looking for heapscans that might need to start from block
zero.
This commit is contained in:
Tom Lane 2008-01-14 02:49:47 +00:00
parent d3b1b1f9d8
commit 66661858ae
1 changed files with 17 additions and 12 deletions

29
contrib/dblink/dblink.c

@ -8,7 +8,7 @@
* Darko Prenosil <Darko.Prenosil@finteh.hr> * Darko Prenosil <Darko.Prenosil@finteh.hr>
* Shridhar Daithankar <shridhar_daithankar@persistent.co.in> * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
* *
* $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.68 2008/01/03 21:27:59 tgl Exp $ * $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.69 2008/01/14 02:49:47 tgl Exp $
* Copyright (c) 2001-2008, PostgreSQL Global Development Group * Copyright (c) 2001-2008, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED; * ALL RIGHTS RESERVED;
* *
@ -38,8 +38,10 @@
#include "fmgr.h" #include "fmgr.h"
#include "funcapi.h" #include "funcapi.h"
#include "miscadmin.h" #include "miscadmin.h"
#include "access/genam.h"
#include "access/heapam.h" #include "access/heapam.h"
#include "access/tupdesc.h" #include "access/tupdesc.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h" #include "catalog/namespace.h"
#include "catalog/pg_index.h" #include "catalog/pg_index.h"
#include "catalog/pg_type.h" #include "catalog/pg_type.h"
@ -1662,8 +1664,8 @@ static char **
get_pkey_attnames(Oid relid, int16 *numatts) get_pkey_attnames(Oid relid, int16 *numatts)
{ {
Relation indexRelation; Relation indexRelation;
ScanKeyData entry; ScanKeyData skey;
HeapScanDesc scan; SysScanDesc scan;
HeapTuple indexTuple; HeapTuple indexTuple;
int i; int i;
char **result = NULL; char **result = NULL;
@ -1671,6 +1673,9 @@ get_pkey_attnames(Oid relid, int16 *numatts)
TupleDesc tupdesc; TupleDesc tupdesc;
AclResult aclresult; AclResult aclresult;
/* initialize numatts to 0 in case no primary key exists */
*numatts = 0;
/* open relation using relid, check permissions, get tupdesc */ /* open relation using relid, check permissions, get tupdesc */
rel = relation_open(relid, AccessShareLock); rel = relation_open(relid, AccessShareLock);
@ -1682,23 +1687,22 @@ get_pkey_attnames(Oid relid, int16 *numatts)
tupdesc = rel->rd_att; tupdesc = rel->rd_att;
/* initialize numatts to 0 in case no primary key exists */ /* Prepare to scan pg_index for entries having indrelid = this rel. */
*numatts = 0;
/* use relid to get all related indexes */
indexRelation = heap_open(IndexRelationId, AccessShareLock); indexRelation = heap_open(IndexRelationId, AccessShareLock);
ScanKeyInit(&entry, ScanKeyInit(&skey,
Anum_pg_index_indrelid, Anum_pg_index_indrelid,
BTEqualStrategyNumber, F_OIDEQ, BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(relid)); ObjectIdGetDatum(relid));
scan = heap_beginscan(indexRelation, SnapshotNow, 1, &entry);
while ((indexTuple = heap_getnext(scan, ForwardScanDirection)) != NULL) scan = systable_beginscan(indexRelation, IndexIndrelidIndexId, true,
SnapshotNow, 1, &skey);
while (HeapTupleIsValid(indexTuple = systable_getnext(scan)))
{ {
Form_pg_index index = (Form_pg_index) GETSTRUCT(indexTuple); Form_pg_index index = (Form_pg_index) GETSTRUCT(indexTuple);
/* we're only interested if it is the primary key */ /* we're only interested if it is the primary key */
if (index->indisprimary == TRUE) if (index->indisprimary)
{ {
*numatts = index->indnatts; *numatts = index->indnatts;
if (*numatts > 0) if (*numatts > 0)
@ -1711,7 +1715,8 @@ get_pkey_attnames(Oid relid, int16 *numatts)
break; break;
} }
} }
heap_endscan(scan);
systable_endscan(scan);
heap_close(indexRelation, AccessShareLock); heap_close(indexRelation, AccessShareLock);
relation_close(rel, AccessShareLock); relation_close(rel, AccessShareLock);