Install a more future-proof fix for the snapshot-unset bug just found.

Per suggestion from Tom Lane.

Author: alvherre

src/backend/postmaster/autovacuum.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.7 2005/11/28 13:35:09 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.8 2005/11/28 17:23:11 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -495,6 +495,9 @@ process_whole_db(void)
 	/* Start a transaction so our commands have one to play into. */
 	StartTransactionCommand();
 
+	 /* functions in indexes may want a snapshot set */
+	ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+
 	dbRel = heap_open(DatabaseRelationId, AccessShareLock);
 
 	/* Must use a table scan, since there's no syscache for pg_database */
@@ -556,6 +559,9 @@ do_autovacuum(PgStat_StatDBEntry *dbentry)
 	/* Start a transaction so our commands have one to play into. */
 	StartTransactionCommand();
 
+	 /* functions in indexes may want a snapshot set */
+	ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+
 	/*
 	 * StartTransactionCommand and CommitTransactionCommand will automatically
 	 * switch to other contexts.  We need this one to keep the list of
@@ -898,14 +904,6 @@ autovacuum_do_vac_analyze(List *relids, bool dovacuum, bool doanalyze,
 	vacstmt->relation = NULL;	/* all tables, or not used if relids != NIL */
 	vacstmt->va_cols = NIL;
 
-	/*
-	 * Functions in indexes may want a snapshot set.  Note we only need
-	 * to do this in limited cases, because it'll be done in vacuum()
-	 * otherwise.
-	 */
-	if (doanalyze && !dovacuum && relids != NIL)
-		ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
-
 	vacuum(vacstmt, relids);
 
 	pfree(vacstmt);