Change pg_amop's index on (amopclaid,amopopr) to index (amopopr,amopclaid).

This makes no difference for existing uses, but allows SelectSortFunction()
and pred_test_simple_clause() to use indexscans instead of seqscans to
locate entries for a particular operator in pg_amop.  Better yet, they can
use the SearchSysCacheList() API to cache the search results.

src/backend/utils/cache/lsyscache.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.93 2003/05/09 18:08:48 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.94 2003/05/13 04:38:58 tgl Exp $
  *
  * NOTES
  *	  Eventually, the index information should go through here, too.
@@ -44,8 +44,8 @@ bool
 op_in_opclass(Oid opno, Oid opclass)
 {
 	return SearchSysCacheExists(AMOPOPID,
-								ObjectIdGetDatum(opclass),
 								ObjectIdGetDatum(opno),
+								ObjectIdGetDatum(opclass),
 								0, 0);
 }
 
@@ -67,8 +67,8 @@ op_requires_recheck(Oid opno, Oid opclass)
 	bool		result;
 
 	tp = SearchSysCache(AMOPOPID,
-						ObjectIdGetDatum(opclass),
 						ObjectIdGetDatum(opno),
+						ObjectIdGetDatum(opclass),
 						0, 0);
 	if (!HeapTupleIsValid(tp))
 		elog(ERROR, "op_requires_recheck: op %u is not a member of opclass %u",

src/backend/utils/cache/syscache.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/syscache.c,v 1.87 2002/09/04 20:31:30 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/syscache.c,v 1.88 2003/05/13 04:38:58 tgl Exp $
  *
  * NOTES
  *	  These routines allow the parser/planner/executor to perform
@@ -128,8 +128,8 @@ static const struct cachedesc cacheinfo[] = {
 		0,
 		2,
 		{
-			Anum_pg_amop_amopclaid,
 			Anum_pg_amop_amopopr,
+			Anum_pg_amop_amopclaid,
 			0,
 			0
 	}},

src/backend/utils/sort/tuplesort.c

@@ -78,7 +78,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/sort/tuplesort.c,v 1.32 2002/11/13 00:39:48 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/sort/tuplesort.c,v 1.33 2003/05/13 04:38:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -87,18 +87,18 @@
 
 #include "access/heapam.h"
 #include "access/nbtree.h"
-#include "catalog/catname.h"
 #include "catalog/pg_amop.h"
 #include "catalog/pg_amproc.h"
 #include "catalog/pg_operator.h"
 #include "miscadmin.h"
+#include "utils/catcache.h"
 #include "utils/datum.h"
-#include "utils/fmgroids.h"
 #include "utils/logtape.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 #include "utils/tuplesort.h"
 
+
 /*
  * Possible states of a Tuplesort object.  These denote the states that
  * persist between calls of Tuplesort routines.
@@ -1708,32 +1708,30 @@ SelectSortFunction(Oid sortOperator,
 				   RegProcedure *sortFunction,
 				   SortFunctionKind *kind)
 {
-	Relation	relation;
-	HeapScanDesc scan;
-	ScanKeyData skey[1];
+	CatCList   *catlist;
+	int			i;
 	HeapTuple	tuple;
 	Form_pg_operator optup;
 	Oid			opclass = InvalidOid;
 
 	/*
-	 * Scan pg_amop to see if the target operator is registered as the "<"
+	 * Search pg_amop to see if the target operator is registered as the "<"
 	 * or ">" operator of any btree opclass.  It's possible that it might
 	 * be registered both ways (eg, if someone were to build a "reverse
 	 * sort" opclass for some reason); prefer the "<" case if so. If the
 	 * operator is registered the same way in multiple opclasses, assume
 	 * we can use the associated comparator function from any one.
 	 */
-	ScanKeyEntryInitialize(&skey[0], 0x0,
-						   Anum_pg_amop_amopopr,
-						   F_OIDEQ,
-						   ObjectIdGetDatum(sortOperator));
+	catlist = SearchSysCacheList(AMOPOPID, 1,
+								 ObjectIdGetDatum(sortOperator),
+								 0, 0, 0);
 
-	relation = heap_openr(AccessMethodOperatorRelationName, AccessShareLock);
-	scan = heap_beginscan(relation, SnapshotNow, 1, skey);
-
-	while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
+	for (i = 0; i < catlist->n_members; i++)
 	{
-		Form_pg_amop aform = (Form_pg_amop) GETSTRUCT(tuple);
+		Form_pg_amop aform;
+
+		tuple = &catlist->members[i]->tuple;
+		aform = (Form_pg_amop) GETSTRUCT(tuple);
 
 		if (!opclass_is_btree(aform->amopclaid))
 			continue;
@@ -1751,8 +1749,7 @@ SelectSortFunction(Oid sortOperator,
 		}
 	}
 
-	heap_endscan(scan);
-	heap_close(relation, AccessShareLock);
+	ReleaseSysCacheList(catlist);
 
 	if (OidIsValid(opclass))
 	{