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

partial.  None of the existing AMs do anything useful except counting
tuples when there's nothing to delete, and we can get a tuple count
from the heap as long as it's not a partial index.  (hash actually can
skip anyway because it maintains a tuple count in the index metapage.)
GIST is not currently able to exploit this optimization because, due to
failure to index NULLs, GIST is always effectively partial.  Possibly
we should fix that sometime.
Simon Riggs w/ some review by Tom Lane.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
index a65c269fc8c..2c1ba517638 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -31,7 +31,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.65 2006/02/11 17:14:09 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.66 2006/02/11 23:31:34 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -625,6 +625,7 @@ lazy_scan_index(Relation indrel, LVRelStats *vacrelstats)
 	/* Do post-VACUUM cleanup, even though we deleted nothing */
 	vcinfo.vacuum_full = false;
 	vcinfo.message_level = elevel;
+	vcinfo.num_heap_tuples = vacrelstats->rel_tuples;
 
 	stats = index_vacuum_cleanup(indrel, &vcinfo, stats);
 
@@ -697,6 +698,9 @@ lazy_vacuum_index(Relation indrel,
 	/* Do post-VACUUM cleanup */
 	vcinfo.vacuum_full = false;
 	vcinfo.message_level = elevel;
+	/* We don't yet know rel_tuples, so pass -1 */
+	/* index_bulk_delete can't have skipped scan anyway ... */
+	vcinfo.num_heap_tuples = -1;
 
 	stats = index_vacuum_cleanup(indrel, &vcinfo, stats);