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authorRobert Haas <rhaas@postgresql.org>2010-06-15 18:43:35 +0000
committerRobert Haas <rhaas@postgresql.org>2010-06-15 18:43:35 +0000
commit4a969085753d4e6586e60e613f160bf3a956b75d (patch)
treee6d56614d3b5a919e55aa50010d4f2a3df39e54c /doc/src
parent48a7245391687cefd21ffe7597eff553f6b29960 (diff)
downloadpostgresql-4a969085753d4e6586e60e613f160bf3a956b75d.tar.gz
postgresql-4a969085753d4e6586e60e613f160bf3a956b75d.zip
Document new 9.0 behavior of ANALYZE on inheritance hierarchies.
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.
Diffstat (limited to 'doc/src')
-rw-r--r--doc/src/sgml/ref/analyze.sgml13
1 files changed, 12 insertions, 1 deletions
diff --git a/doc/src/sgml/ref/analyze.sgml b/doc/src/sgml/ref/analyze.sgml
index 1f2e4c1bad7..98dcbf0ed80 100644
--- a/doc/src/sgml/ref/analyze.sgml
+++ b/doc/src/sgml/ref/analyze.sgml
@@ -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>