Small performance improvement --- use indexscan not heapscan to find

pg_statistic rows to delete while dropping a relation.

diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 076e1e0..930abe0 100644 (file)
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.210 2002/07/18 16:47:22 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.211 2002/07/19 22:21:17 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -793,7 +793,8 @@ heap_create_with_catalog(const char *relname,
  * Formerly, this routine checked for child relations and aborted the
  * deletion if any were found.  Now we rely on the dependency mechanism
  * to check for or delete child relations.  By the time we get here,
- * there are no children and we need only remove the pg_inherits rows.
+ * there are no children and we need only remove any pg_inherits rows
+ * linking this relation to its parent(s).
  */
 static void
 RelationRemoveInheritance(Relation relation)
@@ -1743,21 +1744,25 @@ static void
 RemoveStatistics(Relation rel)
 {
        Relation        pgstatistic;
-       HeapScanDesc scan;
+       SysScanDesc scan;
        ScanKeyData key;
        HeapTuple       tuple;
 
        pgstatistic = heap_openr(StatisticRelationName, RowExclusiveLock);
 
-       ScanKeyEntryInitialize(&key, 0x0, Anum_pg_statistic_starelid,
-                                                  F_OIDEQ,
+       ScanKeyEntryInitialize(&key, 0x0,
+                                                  Anum_pg_statistic_starelid, F_OIDEQ,
                                                   ObjectIdGetDatum(RelationGetRelid(rel)));
-       scan = heap_beginscan(pgstatistic, SnapshotNow, 1, &key);
 
-       while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
+       scan = systable_beginscan(pgstatistic, StatisticRelidAttnumIndex, true,
+                                                         SnapshotNow, 1, &key);
+
+       while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+       {
                simple_heap_delete(pgstatistic, &tuple->t_self);
+       }
 
-       heap_endscan(scan);
+       systable_endscan(scan);
        heap_close(pgstatistic, RowExclusiveLock);
 }