Skip ambulkdelete scan if there's nothing to delete and the index is not

[postgresql] / src / backend / access / nbtree / nbtree.c

diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 4fb70302d7aaf67337e5abddc2a7da60e4ea47e2..e28faef141d83b966f3ba34d7dad669e7ffbdb16 100644 (file)
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.138 2006/02/11 17:14:08 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.139 2006/02/11 23:31:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -564,8 +564,22 @@ btbulkdelete(PG_FUNCTION_ARGS)
         * further to its right, which the indexscan will have no pin on.)      We can
         * skip obtaining exclusive lock on empty pages though, since no indexscan
         * could be stopped on those.
+        *
+        * We can skip the scan entirely if there's nothing to delete (indicated
+        * by callback_state == NULL) and the index isn't partial.  For a partial
+        * index we must scan in order to derive a trustworthy tuple count.
         */
-       buf = _bt_get_endpoint(rel, 0, false);
+       if (callback_state || vac_is_partial_index(rel))
+       {
+               buf = _bt_get_endpoint(rel, 0, false);
+       }
+       else
+       {
+               /* skip scan and set flag for btvacuumcleanup */
+               buf = InvalidBuffer;
+               num_index_tuples = -1;
+       }
+
        if (BufferIsValid(buf))         /* check for empty index */
        {
                for (;;)
@@ -836,6 +850,13 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
        stats->pages_deleted = pages_deleted;
        stats->pages_free = nFreePages;
 
+       /* if btbulkdelete skipped the scan, use heap's tuple count */
+       if (stats->num_index_tuples < 0)
+       {
+               Assert(info->num_heap_tuples >= 0);
+               stats->num_index_tuples = info->num_heap_tuples;
+       }
+
        PG_RETURN_POINTER(stats);
 }