Change search for default operator classes so that it examines all opclasses

regardless of the current schema search path.  Since CREATE OPERATOR CLASS
only allows one default opclass per datatype regardless of schemas, this
should have minimal impact, and it fixes problems with failure to find a
desired opclass while restoring dump files.  Per discussion at
http://archives.postgresql.org/pgsql-hackers/2006-02/msg00284.php.
Remove now-redundant-or-unused code in typcache.c and namespace.c,
and backpatch as far as 8.0.

Author: tglsfdc

src/backend/catalog/namespace.c

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.80 2005/11/22 18:17:08 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.81 2006/02/10 19:01:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -911,119 +911,6 @@ OperatorIsVisible(Oid oprid)
 }
 
 
-/*
- * OpclassGetCandidates
- *		Given an index access method OID, retrieve a list of all the
- *		opclasses for that AM that are visible in the search path.
- *
- * NOTE: the opcname_tmp field in the returned structs should not be used
- * by callers, because it points at syscache entries that we release at
- * the end of this routine.  If any callers needed the name information,
- * we could pstrdup() the names ... but at present it'd be wasteful.
- */
-OpclassCandidateList
-OpclassGetCandidates(Oid amid)
-{
-	OpclassCandidateList resultList = NULL;
-	CatCList   *catlist;
-	int			i;
-
-	/* Search syscache by AM OID only */
-	catlist = SearchSysCacheList(CLAAMNAMENSP, 1,
-								 ObjectIdGetDatum(amid),
-								 0, 0, 0);
-
-	recomputeNamespacePath();
-
-	for (i = 0; i < catlist->n_members; i++)
-	{
-		HeapTuple	opctup = &catlist->members[i]->tuple;
-		Form_pg_opclass opcform = (Form_pg_opclass) GETSTRUCT(opctup);
-		int			pathpos = 0;
-		OpclassCandidateList newResult;
-		ListCell   *nsp;
-
-		/* Consider only opclasses that are in the search path */
-		foreach(nsp, namespaceSearchPath)
-		{
-			if (opcform->opcnamespace == lfirst_oid(nsp))
-				break;
-			pathpos++;
-		}
-		if (nsp == NULL)
-			continue;			/* opclass is not in search path */
-
-		/*
-		 * Okay, it's in the search path, but does it have the same name as
-		 * something we already accepted?  If so, keep only the one that
-		 * appears earlier in the search path.
-		 *
-		 * If we have an ordered list from SearchSysCacheList (the normal
-		 * case), then any conflicting opclass must immediately adjoin this
-		 * one in the list, so we only need to look at the newest result item.
-		 * If we have an unordered list, we have to scan the whole result
-		 * list.
-		 */
-		if (resultList)
-		{
-			OpclassCandidateList prevResult;
-
-			if (catlist->ordered)
-			{
-				if (strcmp(NameStr(opcform->opcname),
-						   resultList->opcname_tmp) == 0)
-					prevResult = resultList;
-				else
-					prevResult = NULL;
-			}
-			else
-			{
-				for (prevResult = resultList;
-					 prevResult;
-					 prevResult = prevResult->next)
-				{
-					if (strcmp(NameStr(opcform->opcname),
-							   prevResult->opcname_tmp) == 0)
-						break;
-				}
-			}
-			if (prevResult)
-			{
-				/* We have a match with a previous result */
-				Assert(pathpos != prevResult->pathpos);
-				if (pathpos > prevResult->pathpos)
-					continue;	/* keep previous result */
-				/* replace previous result */
-				prevResult->opcname_tmp = NameStr(opcform->opcname);
-				prevResult->pathpos = pathpos;
-				prevResult->oid = HeapTupleGetOid(opctup);
-				prevResult->opcintype = opcform->opcintype;
-				prevResult->opcdefault = opcform->opcdefault;
-				prevResult->opckeytype = opcform->opckeytype;
-				continue;
-			}
-		}
-
-		/*
-		 * Okay to add it to result list
-		 */
-		newResult = (OpclassCandidateList)
-			palloc(sizeof(struct _OpclassCandidateList));
-		newResult->opcname_tmp = NameStr(opcform->opcname);
-		newResult->pathpos = pathpos;
-		newResult->oid = HeapTupleGetOid(opctup);
-		newResult->opcintype = opcform->opcintype;
-		newResult->opcdefault = opcform->opcdefault;
-		newResult->opckeytype = opcform->opckeytype;
-		newResult->next = resultList;
-		resultList = newResult;
-	}
-
-	ReleaseSysCacheList(catlist);
-
-	return resultList;
-}
-
 /*
  * OpclassnameGetOpcid
  *		Try to resolve an unqualified index opclass name.

src/backend/commands/indexcmds.c

@@ -8,37 +8,36 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.136 2005/11/22 18:17:09 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.137 2006/02/10 19:01:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 
 #include "postgres.h"
 
+#include "access/genam.h"
 #include "access/heapam.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
 #include "catalog/heap.h"
 #include "catalog/index.h"
-#include "catalog/namespace.h"
+#include "catalog/indexing.h"
 #include "catalog/pg_opclass.h"
-#include "catalog/pg_proc.h"
 #include "catalog/pg_tablespace.h"
 #include "commands/dbcommands.h"
 #include "commands/defrem.h"
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
-#include "executor/executor.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "optimizer/clauses.h"
-#include "optimizer/prep.h"
 #include "parser/parsetree.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
 #include "parser/parse_func.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
+#include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/relcache.h"
@@ -54,7 +53,6 @@ static void ComputeIndexAttrs(IndexInfo *indexInfo, Oid *classOidP,
 				  bool isconstraint);
 static Oid GetIndexOpClass(List *opclass, Oid attrType,
 				char *accessMethodName, Oid accessMethodId);
-static Oid	GetDefaultOpClass(Oid attrType, Oid accessMethodId);
 static bool relationHasPrimaryKey(Relation rel);
 
 
@@ -658,17 +656,26 @@ GetIndexOpClass(List *opclass, Oid attrType,
 	return opClassId;
 }
 
-static Oid
-GetDefaultOpClass(Oid attrType, Oid accessMethodId)
+/*
+ * GetDefaultOpClass
+ *
+ * Given the OIDs of a datatype and an access method, find the default
+ * operator class, if any.	Returns InvalidOid if there is none.
+ */
+Oid
+GetDefaultOpClass(Oid type_id, Oid am_id)
 {
-	OpclassCandidateList opclass;
 	int			nexact = 0;
 	int			ncompatible = 0;
 	Oid			exactOid = InvalidOid;
 	Oid			compatibleOid = InvalidOid;
+	Relation	rel;
+	ScanKeyData skey[1];
+	SysScanDesc scan;
+	HeapTuple	tup;
 
 	/* If it's a domain, look at the base type instead */
-	attrType = getBaseType(attrType);
+	type_id = getBaseType(type_id);
 
 	/*
 	 * We scan through all the opclasses available for the access method,
@@ -678,37 +685,47 @@ GetDefaultOpClass(Oid attrType, Oid accessMethodId)
 	 * We could find more than one binary-compatible match, in which case we
 	 * require the user to specify which one he wants.	If we find more than
 	 * one exact match, then someone put bogus entries in pg_opclass.
-	 *
-	 * The initial search is done by namespace.c so that we only consider
-	 * opclasses visible in the current namespace search path.	(See also
-	 * typcache.c, which applies the same logic, but over all opclasses.)
 	 */
-	for (opclass = OpclassGetCandidates(accessMethodId);
-		 opclass != NULL;
-		 opclass = opclass->next)
+	rel = heap_open(OperatorClassRelationId, AccessShareLock);
+
+	ScanKeyInit(&skey[0],
+				Anum_pg_opclass_opcamid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(am_id));
+
+	scan = systable_beginscan(rel, OpclassAmNameNspIndexId, true,
+							  SnapshotNow, 1, skey);
+
+	while (HeapTupleIsValid(tup = systable_getnext(scan)))
 	{
+		Form_pg_opclass opclass = (Form_pg_opclass) GETSTRUCT(tup);
+
 		if (opclass->opcdefault)
 		{
-			if (opclass->opcintype == attrType)
+			if (opclass->opcintype == type_id)
 			{
 				nexact++;
-				exactOid = opclass->oid;
+				exactOid = HeapTupleGetOid(tup);
 			}
-			else if (IsBinaryCoercible(attrType, opclass->opcintype))
+			else if (IsBinaryCoercible(type_id, opclass->opcintype))
 			{
 				ncompatible++;
-				compatibleOid = opclass->oid;
+				compatibleOid = HeapTupleGetOid(tup);
 			}
 		}
 	}
 
+	systable_endscan(scan);
+
+	heap_close(rel, AccessShareLock);
+
 	if (nexact == 1)
 		return exactOid;
 	if (nexact != 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DUPLICATE_OBJECT),
 		errmsg("there are multiple default operator classes for data type %s",
-			   format_type_be(attrType))));
+			   format_type_be(type_id))));
 	if (ncompatible == 1)
 		return compatibleOid;