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

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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.
This commit is contained in:
Tom Lane
2007-09-20 17:56:33 +00:00
parent bbf4fdc253
commit 282d2a03dd
65 changed files with 3517 additions and 514 deletions
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7
src/backend/nodes/tidbitmap.c
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@ -23,7 +23,7 @@
* Copyright (c) 2003-2007, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.12 2007/04/26 23:24:44 tgl Exp $
* $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.13 2007/09/20 17:56:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -32,6 +32,7 @@
#include <limits.h>
#include "access/htup.h"
#include "nodes/bitmapset.h"
#include "nodes/tidbitmap.h"
#include "storage/bufpage.h"
#include "utils/hsearch.h"
@ -61,9 +62,7 @@
*/
#define PAGES_PER_CHUNK (BLCKSZ / 32)
/* The bitmap unit size can be adjusted by changing these declarations: */
#define BITS_PER_BITMAPWORD 32
typedef uint32 bitmapword; /* must be an unsigned type */
/* We use BITS_PER_BITMAPWORD and typedef bitmapword from nodes/bitmapset.h */
#define WORDNUM(x) ((x) / BITS_PER_BITMAPWORD)
#define BITNUM(x) ((x) % BITS_PER_BITMAPWORD)