Wrap calls to SearchSysCache and related functions using macros.

The purpose of this change is to eliminate the need for every caller
of SearchSysCache, SearchSysCacheCopy, SearchSysCacheExists,
GetSysCacheOid, and SearchSysCacheList to know the maximum number
of allowable keys for a syscache entry (currently 4).  This will
make it far easier to increase the maximum number of keys in a
future release should we choose to do so, and it makes the code
shorter, too.

Design and review by Tom Lane.

Author: robertmhaas

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 1.88 2010/02/03 23:01:11 joe Exp $
+ * $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.89 2010/02/14 18:42:11 rhaas Exp $
  * Copyright (c) 2001-2010, PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  *
@@ -2180,9 +2180,7 @@ generate_relation_name(Oid relid)
 	char	   *nspname;
 	char	   *result;
 
-	tp = SearchSysCache(RELOID,
-						ObjectIdGetDatum(relid),
-						0, 0, 0);
+	tp = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
 	if (!HeapTupleIsValid(tp))
 		elog(ERROR, "cache lookup failed for relation %u", relid);
 

src/backend/access/common/tupdesc.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/common/tupdesc.c,v 1.132 2010/01/22 16:40:18 rhaas Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/common/tupdesc.c,v 1.133 2010/02/14 18:42:12 rhaas Exp $
  *
  * NOTES
  *	  some of the executor utility code such as "ExecTypeFromTL" should be
@@ -478,9 +478,7 @@ TupleDescInitEntry(TupleDesc desc,
 	att->attinhcount = 0;
 	/* attacl and attoptions are not present in tupledescs */
 
-	tuple = SearchSysCache(TYPEOID,
-						   ObjectIdGetDatum(oidtypeid),
-						   0, 0, 0);
+	tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(oidtypeid));
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "cache lookup failed for type %u", oidtypeid);
 	typeForm = (Form_pg_type) GETSTRUCT(tuple);

src/backend/access/heap/heapam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.286 2010/02/08 04:33:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.287 2010/02/14 18:42:12 rhaas Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -935,9 +935,7 @@ try_relation_open(Oid relationId, LOCKMODE lockmode)
 	 * Now that we have the lock, probe to see if the relation really exists
 	 * or not.
 	 */
-	if (!SearchSysCacheExists(RELOID,
-							  ObjectIdGetDatum(relationId),
-							  0, 0, 0))
+	if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(relationId)))
 	{
 		/* Release useless lock */
 		if (lockmode != NoLock)

src/backend/access/transam/varsup.c

@@ -6,7 +6,7 @@
  * Copyright (c) 2000-2010, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/transam/varsup.c,v 1.87 2010/01/02 16:57:35 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/transam/varsup.c,v 1.88 2010/02/14 18:42:12 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -402,9 +402,7 @@ ForceTransactionIdLimitUpdate(void)
 	if (TransactionIdFollowsOrEquals(nextXid, xidVacLimit) &&
 		TransactionIdIsValid(xidVacLimit))
 		return true;			/* past VacLimit, don't delay updating */
-	if (!SearchSysCacheExists(DATABASEOID,
-							  ObjectIdGetDatum(oldestXidDB),
-							  0, 0, 0))
+	if (!SearchSysCacheExists1(DATABASEOID, ObjectIdGetDatum(oldestXidDB)))
 		return true;			/* could happen, per comments above */
 	return false;
 }