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 076e1e0462bc3346795f7ea943f50c659d7eea17..930abe00f853d88c6f5fcbe9c584a6bd6b90226b 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);
 }