to the view's <structfield>query</structfield> column will return nulls).  This
      feature is intended to support external tools that might wish to avoid
      the overhead of repeatedly retrieving query texts of indeterminate
      length.  Such tools can instead cache the first query text observed
      for each entry themselves, since that is
      all <filename>pg_stat_statements</filename> itself does, and then retrieve
      query texts only as needed.  Since the server stores query texts in a
      file, this approach may reduce physical I/O for repeated examination
      of the <structname>pg_stat_statements</structname> data.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </sect2>

 <sect2 id="pgstatstatements-config-params">
  <title>Configuration Parameters</title>

  <variablelist>
   <varlistentry>
    <term>
     <varname>pg_stat_statements.max</varname> (<type>integer</type>)
     <indexterm>
      <primary><varname>pg_stat_statements.max</varname> configuration parameter</primary>
     </indexterm>
    </term>

    <listitem>
     <para>
      <varname>pg_stat_statements.max</varname> is the maximum number of
      statements tracked by the module (i.e., the maximum number of rows
      in the <structname>pg_stat_statements</structname> view).  If more distinct
      statements than that are observed, information about the least-executed
      statements is discarded.  The number of times such information was
      discarded can be seen in the
      <structname>pg_stat_statements_info</structname> view.
      The default value is 5000.
      This parameter can only be set at server start.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     <varname>pg_stat_statements.track</varname> (<type>enum</type>)
     <indexterm>
      <primary><varname>pg_stat_statements.track</varname> configuration parameter</primary>
     </indexterm>
    </term>

    <listitem>
     <para>
      <varname>pg_stat_statements.track</varname> controls which statements
      are counted by the module.
      Specify <literal>top</literal> to track top-level statements (those issued
      directly by clients), <literal>all</literal> to also track nested statements
      (such as statements invoked within functions), or <literal>none</literal> to
      disable statement statistics collection.
      The default value is <literal>top</literal>.
      Only superusers can change this setting.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     <varname>pg_stat_statements.track_utility</varname> (<type>boolean</type>)
     <indexterm>
      <primary><varname>pg_stat_statements.track_utility</varname> configuration parameter</primary>
     </indexterm>
    </term>

    <listitem>
     <para>
      <varname>pg_stat_statements.track_utility</varname> controls whether
      utility commands are tracked by the module.  Utility commands are
      all those other than <command>SELECT</command>, <command>INSERT</command>,
      <command>UPDATE</command>, <command>DELETE</command>, and <command>MERGE</command>.
      The default value is <literal>on</literal>.
      Only superusers can change this setting.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     <varname>pg_stat_statements.track_planning</varname> (<type>boolean</type>)
     <indexterm>
      <primary><varname>pg_stat_statements.track_planning</varname> configuration parameter</primary>
     </indexterm>
    </term>

    <listitem>
     <para>
      <varname>pg_stat_statements.track_planning</varname> controls whether
      planning operations and duration are tracked by the module.
      Enabling this parameter may incur a noticeable performance penalty,
      especially when statements with identical query structure are executed
      by many concurrent connections which compete to update a small number of
      <structname>pg_stat_statements</structname> entries.
      The default