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+$Header: /cvsroot/pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.8 2000/04/05 21:51:11 momjian Exp $
Postgres documentation
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<para>
Updates column statistics used by the optimizer to
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>
</listitem>
</varlistentry>
tuples and number of pages stored in all classes.
</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>
Running <command>VACUUM</command>
periodically will increase the speed of the database in processing user queries.
query may be executed at any time, however. In particular, after
copying a large class into <productname>Postgres</productname>
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
recent changes, and allow the <productname>Postgres</productname>
query optimizer to make better choices in planning user queries.
</para>
+
</refsect2>
</refsect1>