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Update vacuum to mention analyze

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Bruce Momjian 2000-04-05 21:51:11 +00:00
parent a7b1ff6619
commit 7c6bac0071
1 changed files with 10 additions and 4 deletions
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doc/src/sgml/ref/vacuum.sgml
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@ -1,5 +1,5 @@
<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.7 1999/12/07 22:41:41 momjian Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.8 2000/04/05 21:51:11 momjian Exp $
Postgres documentation Postgres documentation
--> -->
@ -51,8 +51,6 @@ VACUUM [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">table</replaceable>
<para> <para>
Updates column statistics used by the optimizer to Updates column statistics used by the optimizer to
determine the most efficient way to execute a query. determine the most efficient way to execute a query.
The statistics represent the disbursion of the data in each column.
This information is valuable when several execution paths are possible.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -158,6 +156,13 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28;
tuples and number of pages stored in all classes. tuples and number of pages stored in all classes.
</para> </para>
<para>
<command>VACUUM ANALYZE</command> collects statistics representing the
disbursion of the data in each column.
This information is valuable when several query execution paths are possible.
</para>
<para> <para>
Running <command>VACUUM</command> Running <command>VACUUM</command>
periodically will increase the speed of the database in processing user queries. periodically will increase the speed of the database in processing user queries.
@ -179,11 +184,12 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28;
query may be executed at any time, however. In particular, after query may be executed at any time, however. In particular, after
copying a large class into <productname>Postgres</productname> copying a large class into <productname>Postgres</productname>
or after deleting a large number of or after deleting a large number of
records, it may be a good idea to issue a <command>VACUUM</command> records, it may be a good idea to issue a <command>VACUUM ANALYZE</command>
query. This will update the system catalogs with the results of all query. This will update the system catalogs with the results of all
recent changes, and allow the <productname>Postgres</productname> recent changes, and allow the <productname>Postgres</productname>
query optimizer to make better choices in planning user queries. query optimizer to make better choices in planning user queries.
</para> </para>
</refsect2> </refsect2>
</refsect1> </refsect1>