diff options
Diffstat (limited to 'doc/src/sgml/ref/vacuum.sgml')
| -rw-r--r-- | doc/src/sgml/ref/vacuum.sgml | 48 |
1 files changed, 38 insertions, 10 deletions
diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml index 7ce61b72cc8..e8374725b34 100644 --- a/doc/src/sgml/ref/vacuum.sgml +++ b/doc/src/sgml/ref/vacuum.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.16 2001/05/25 15:45:31 momjian Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.17 2001/07/10 22:09:28 tgl Exp $ Postgres documentation --> @@ -20,16 +20,16 @@ Postgres documentation </refnamediv> <refsynopsisdiv> <refsynopsisdivinfo> - <date>2001-05-04</date> + <date>2001-07-10</date> </refsynopsisdivinfo> <synopsis> -VACUUM [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> ] -VACUUM [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">table</replaceable> [ (<replaceable class="PARAMETER">column</replaceable> [, ...] ) ] ] +VACUUM [ FULL ] [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> ] +VACUUM [ FULL ] [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">table</replaceable> [ (<replaceable class="PARAMETER">column</replaceable> [, ...] ) ] ] </synopsis> <refsect2 id="R2-SQL-VACUUM-1"> <refsect2info> - <date>1998-10-04</date> + <date>2001-07-10</date> </refsect2info> <title> Inputs @@ -38,6 +38,15 @@ VACUUM [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">table</replaceable> <para> <variablelist> <varlistentry> + <term>FULL</term> + <listitem> + <para> + Selects <quote>full</quote> vacuum, which may reclaim more space, + but takes much longer and exclusively locks the table. + </para> + </listitem> + </varlistentry> + <varlistentry> <term>VERBOSE</term> <listitem> <para> @@ -58,7 +67,8 @@ VACUUM [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">table</replaceable> <term><replaceable class="PARAMETER">table</replaceable></term> <listitem> <para> - The name of a specific table to vacuum. Defaults to all tables. + The name of a specific table to vacuum. Defaults to all tables + in the current database. </para> </listitem> </varlistentry> @@ -138,7 +148,7 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; <refsect1 id="R1-SQL-VACUUM-1"> <refsect1info> - <date>1998-10-04</date> + <date>2001-07-10</date> </refsect1info> <title> Description @@ -159,6 +169,16 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; </para> <para> + Plain <command>VACUUM</command> simply reclaims space and makes it + available for re-use. This form of the command can operate in parallel + with normal reading and writing of the table. <command>VACUUM + FULL</command> does more extensive processing, including moving of tuples + across blocks to try to compact the table to the minimum number of disk + blocks. This is much slower and requires an exclusive lock on each table + while it is being processed. + </para> + + <para> <command>VACUUM ANALYZE</command> performs a <command>VACUUM</command> and then an <command>ANALYZE</command> for each selected table. This is a handy combination form for routine maintenance scripts. See @@ -168,7 +188,7 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; <refsect2 id="R2-SQL-VACUUM-3"> <refsect2info> - <date>1998-10-04</date> + <date>2001-07-10</date> </refsect2info> <title> Notes @@ -176,8 +196,8 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; <para> We recommend that active production databases be - <command>VACUUM</command>-ed nightly, in order to remove - expired rows. After copying a large table into + <command>VACUUM</command>-ed frequently (at least nightly), in order to + remove expired rows. After copying a large table into <productname>Postgres</productname> or after deleting a large number of records, it may be a good idea to issue a <command>VACUUM ANALYZE</command> command for the affected table. This will update the @@ -187,6 +207,14 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; choices in planning user queries. </para> + <para> + The <option>FULL</option> option is not recommended for routine use, + but may be useful in special cases. An example is when you have deleted + most of the rows in a table and would like the table to physically shrink + to occupy less disk space. <command>VACUUM FULL</command> will usually + shrink the table more than a plain <command>VACUUM</command> would. + </para> + </refsect2> </refsect1> |