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<title>17.9.Automatic Vacuuming</title>
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="runtime-config-autovacuum"></a>17.9.Automatic Vacuuming</h2></div></div></div>
<a name="id653012"></a><p> These settings control the default behavior for the <em class="firstterm">autovacuum
daemon</em>. Please refer to <a href="maintenance.html#autovacuum" title="22.1.4.The auto-vacuum daemon">Section22.1.4, “The auto-vacuum daemon”</a> for
more information.
</p>
<div class="variablelist"><dl>
<dt>
<a name="guc-autovacuum"></a><span class="term"><code class="varname">autovacuum</code> (<code class="type">boolean</code>)</span>
</dt>
<dd><p> Controls whether the server should start the
autovacuum subprocess. This is off by default.
<code class="varname">stats_start_collector</code> and <code class="varname">stats_row_level</code>
must also be on for this to start.
This option can be set at server start or in the
<code class="filename">postgresql.conf</code> file.
</p></dd>
<dt>
<a name="guc-autovacuum-naptime"></a><span class="term"><code class="varname">autovacuum_naptime</code> (<code class="type">integer</code>)</span>
</dt>
<dd><p> Specifies the delay between activity rounds for the autovacuum
subprocess. In each round the subprocess examines one database
and issues <code class="command">VACUUM</code> and <code class="command">ANALYZE</code> commands
as needed for tables in that database. The delay is measured
in seconds, and the default is 60.
This option can be set at server start or in the
<code class="filename">postgresql.conf</code> file.
</p></dd>
<dt>
<a name="guc-autovacuum-vacuum-threshold"></a><span class="term"><code class="varname">autovacuum_vacuum_threshold</code> (<code class="type">integer</code>)</span>
</dt>
<dd><p> Specifies the minimum number of updated or deleted tuples needed
to trigger a <code class="command">VACUUM</code> in any one table.
The default is 1000.
This option can be set at server start or in the
<code class="filename">postgresql.conf</code> file.
This setting can be overridden for individual tables by entries in
<code class="structname">pg_autovacuum</code>.
</p></dd>
<dt>
<a name="guc-autovacuum-analyze-threshold"></a><span class="term"><code class="varname">autovacuum_analyze_threshold</code> (<code class="type">integer</code>)</span>
</dt>
<dd><p> Specifies the minimum number of inserted, updated or deleted tuples
needed to trigger an <code class="command">ANALYZE</code> in any one table.
The default is 500.
This option can be set at server start or in the
<code class="filename">postgresql.conf</code> file.
This setting can be overridden for individual tables by entries in
<code class="structname">pg_autovacuum</code>.
</p></dd>
<dt>
<a name="guc-autovacuum-vacuum-scale-factor"></a><span class="term"><code class="varname">autovacuum_vacuum_scale_factor</code> (<code class="type">floating point</code>)</span>
</dt>
<dd><p> Specifies a fraction of the table size to add to
<code class="varname">autovacuum_vacuum_threshold</code>
when deciding whether to trigger a <code class="command">VACUUM</code>.
The default is 0.4.
This option can be set at server start or in the
<code class="filename">postgresql.conf</code> file.
This setting can be overridden for individual tables by entries in
<code class="structname">pg_autovacuum</code>.
</p></dd>
<dt>
<a name="guc-autovacuum-analyze-scale-factor"></a><span class="term"><code class="varname">autovacuum_analyze_scale_factor</code> (<code class="type">floating point</code>)</span>
</dt>
<dd><p> Specifies a fraction of the table size to add to
<code class="varname">autovacuum_analyze_threshold</code>
when deciding whether to trigger an <code class="command">ANALYZE</code>.
The default is 0.2.
This option can be set at server start or in the
<code class="filename">postgresql.conf</code> file.
This setting can be overridden for individual tables by entries in
<code class="structname">pg_autovacuum</code>.
</p></dd>
<dt>
<a name="guc-autovacuum-vacuum-cost-delay"></a><span class="term"><code class="varname">autovacuum_vacuum_cost_delay</code> (<code class="type">integer</code>)</span>
</dt>
<dd><p> Specifies the cost delay value that will be used in automatic
<code class="command">VACUUM</code> operations. If -1 is specified (which is the
default), the regular
<a href="runtime-config-resource.html#guc-vacuum-cost-delay">vacuum_cost_delay</a> value will be used.
This setting can be overridden for individual tables by entries in
<code class="structname">pg_autovacuum</code>.
</p></dd>
<dt>
<a name="guc-autovacuum-vacuum-cost-limit"></a><span class="term"><code class="varname">autovacuum_vacuum_cost_limit</code> (<code class="type">integer</code>)</span>
</dt>
<dd><p> Specifies the cost limit value that will be used in automatic
<code class="command">VACUUM</code> operations. If -1 is specified (which is the
default), the regular
<a href="runtime-config-resource.html#guc-vacuum-cost-limit">vacuum_cost_limit</a> value will be used.
This setting can be overridden for individual tables by entries in
<code class="structname">pg_autovacuum</code>.
</p></dd>
</dl></div>
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