HOT updates. When we update a tuple without changing any of its indexed

columns, and the new version can be stored on the same heap page, we no longer
generate extra index entries for the new version.  Instead, index searches
follow the HOT-chain links to ensure they find the correct tuple version.

In addition, this patch introduces the ability to "prune" dead tuples on a
per-page basis, without having to do a complete VACUUM pass to recover space.
VACUUM is still needed to clean up dead index entries, however.

Pavan Deolasee, with help from a bunch of other people.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 7a4190d044b..1324befa1e2 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.106 2007/07/25 12:22:53 mha Exp $
+ * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.107 2007/09/20 17:56:32 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -156,6 +156,7 @@ extern void UnlockBuffers(void);
 extern void LockBuffer(Buffer buffer, int mode);
 extern bool ConditionalLockBuffer(Buffer buffer);
 extern void LockBufferForCleanup(Buffer buffer);
+extern bool ConditionalLockBufferForCleanup(Buffer buffer);
 
 extern void AbortBufferIO(void);