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

Noted while looking for heapscans that might need to start from block
zero.

diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index 92891a035570624985d2725833262838005a3dda..e09d6f16f6973c037ad4f544566f51ee1efcb17d 100644 (file)
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -8,7 +8,7 @@
  * Darko Prenosil <Darko.Prenosil@finteh.hr>
  * 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
  * ALL RIGHTS RESERVED;
  *
@@ -38,8 +38,10 @@
 #include "fmgr.h"
 #include "funcapi.h"
 #include "miscadmin.h"
+#include "access/genam.h"
 #include "access/heapam.h"
 #include "access/tupdesc.h"
+#include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_index.h"
 #include "catalog/pg_type.h"
@@ -1662,8 +1664,8 @@ static char **
 get_pkey_attnames(Oid relid, int16 *numatts)
 {
    Relation    indexRelation;
-   ScanKeyData entry;
-   HeapScanDesc scan;
+   ScanKeyData skey;
+   SysScanDesc scan;
    HeapTuple   indexTuple;
    int         i;
    char      **result = NULL;
@@ -1671,6 +1673,9 @@ get_pkey_attnames(Oid relid, int16 *numatts)
    TupleDesc   tupdesc;
    AclResult   aclresult;
 
+   /* initialize numatts to 0 in case no primary key exists */
+   *numatts = 0;
+
    /* open relation using relid, check permissions, get tupdesc */
    rel = relation_open(relid, AccessShareLock);
 
@@ -1682,23 +1687,22 @@ get_pkey_attnames(Oid relid, int16 *numatts)
 
    tupdesc = rel->rd_att;
 
-   /* initialize numatts to 0 in case no primary key exists */
-   *numatts = 0;
-
-   /* use relid to get all related indexes */
+   /* Prepare to scan pg_index for entries having indrelid = this rel. */
    indexRelation = heap_open(IndexRelationId, AccessShareLock);
-   ScanKeyInit(&entry,
+   ScanKeyInit(&skey,
                Anum_pg_index_indrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                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);
 
        /* we're only interested if it is the primary key */
-       if (index->indisprimary == TRUE)
+       if (index->indisprimary)
        {
            *numatts = index->indnatts;
            if (*numatts > 0)
@@ -1711,7 +1715,8 @@ get_pkey_attnames(Oid relid, int16 *numatts)
            break;
        }
    }
-   heap_endscan(scan);
+
+   systable_endscan(scan);
    heap_close(indexRelation, AccessShareLock);
    relation_close(rel, AccessShareLock);