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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
doc/src/sgml/ref/create_index.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_index.sgml,v 1.64 2007/09/07 00:58:56 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/create_index.sgml,v 1.65 2007/09/20 17:56:30 tgl Exp $
PostgreSQL documentation
-->
@ -329,7 +329,10 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] <replaceable class="parameter">name</re
</para>
<para>
If a problem arises during the second scan of the table, such as a
In a concurrent index build, the index is actually entered into the
system catalogs in one transaction, then the two table scans occur in a
second and third transaction.
If a problem arises while scanning the table, such as a
uniqueness violation in a unique index, the <command>CREATE INDEX</>
command will fail but leave behind an <quote>invalid</> index. This index
will be ignored for querying purposes because it might be incomplete;