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Document new 9.0 behavior of ANALYZE on inheritance hierarchies.

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In particular, note that autovacuum does not yet understand that it might
need to vacuum inheritance parents as a result of changes to the child
tables.
This commit is contained in:
Robert Haas 2010-06-15 18:43:35 +00:00
parent 48a7245391
commit 4a96908575
1 changed files with 12 additions and 1 deletions
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13
doc/src/sgml/ref/analyze.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/analyze.sgml,v 1.29 2010/04/03 07:22:57 petere Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/analyze.sgml,v 1.30 2010/06/15 18:43:35 rhaas Exp $
PostgreSQL documentation
-->
@ -176,6 +176,17 @@ ANALYZE [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> [ ( <re
<command>ALTER TABLE ... ALTER COLUMN ... SET (n_distinct = ...)</>
(see <xref linkend="sql-altertable">).
</para>
<para>
If the table being analyzed has one or more children,
<command>ANALYZE</command> will gather statistics twice: once on the
rows of the parent table only, and a second time on the rows of the
parent table with all of its children. The autovacuum daemon, however,
will only consider inserts or updates on the parent table when deciding
whether to trigger an automatic analyze. If that table is rarely
inserted into or updated, the inheritance statistics will not be up to date
unless you run <command>ANALYZE</command> manually.
</para>
</refsect1>
<refsect1>