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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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6
src/backend/executor/execMain.c
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@ -26,7 +26,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.297 2007/09/07 20:59:26 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.298 2007/09/20 17:56:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1813,8 +1813,10 @@ lreplace:;
*
* Note: heap_update returns the tid (location) of the new tuple in the
* t_self field.
*
* If it's a HOT update, we mustn't insert new index entries.
*/
if (resultRelInfo->ri_NumIndices > 0)
if (resultRelInfo->ri_NumIndices > 0 && !HeapTupleIsHeapOnly(tuple))
ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
/* AFTER ROW UPDATE Triggers */