xreflabel="enable_memoize">
      <term><varname>enable_memoize</varname> (<type>boolean</type>)
      <indexterm>
       <primary><varname>enable_memoize</varname> configuration parameter</primary>
      </indexterm>
      </term>
      <listitem>
       <para>
        Enables or disables the query planner's use of memoize plans for
        caching results from parameterized scans inside nested-loop joins.
        This plan type allows scans to the underlying plans to be skipped when
        the results for the current parameters are already in the cache.  Less
        commonly looked up results may be evicted from the cache when more
        space is required for new entries. The default is
        <literal>on</literal>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-enable-mergejoin" xreflabel="enable_mergejoin">
      <term><varname>enable_mergejoin</varname> (<type>boolean</type>)
      <indexterm>
       <primary><varname>enable_mergejoin</varname> configuration parameter</primary>
      </indexterm>
      </term>
      <listitem>
       <para>
        Enables or disables the query planner's use of merge-join plan
        types. The default is <literal>on</literal>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-enable-nestloop" xreflabel="enable_nestloop">
      <term><varname>enable_nestloop</varname> (<type>boolean</type>)
      <indexterm>
       <primary><varname>enable_nestloop</varname> configuration parameter</primary>
      </indexterm>
      </term>
      <listitem>
       <para>
        Enables or disables the query planner's use of nested-loop join
        plans. It is impossible to suppress nested-loop joins entirely,
        but turning this variable off discourages the planner from using
        one if there are other methods available. The default is
        <literal>on</literal>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-enable-parallel-append" xreflabel="enable_parallel_append">
      <term><varname>enable_parallel_append</varname> (<type>boolean</type>)
      <indexterm>
       <primary><varname>enable_parallel_append</varname> configuration parameter</primary>
      </indexterm>
      </term>
      <listitem>
       <para>
        Enables or disables the query planner's use of parallel-aware
        append plan types. The default is <literal>on</literal>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-enable-parallel-hash" xreflabel="enable_parallel_hash">
      <term><varname>enable_parallel_hash</varname> (<type>boolean</type>)
       <indexterm>
        <primary><varname>enable_parallel_hash</varname> configuration parameter</primary>
       </indexterm>
      </term>
      <listitem>
       <para>
        Enables or disables the query planner's use of hash-join plan
        types with parallel hash. Has no effect if hash-join plans are not
        also enabled. The default is <literal>on</literal>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-enable-partition-pruning" xreflabel="enable_partition_pruning">
      <term><varname>enable_partition_pruning</varname> (<type>boolean</type>)
       <indexterm>
        <primary><varname>enable_partition_pruning</varname> configuration parameter</primary>
       </indexterm>
      </term>
      <listitem>
       <para>
        Enables or disables the query planner's ability to eliminate a
        partitioned table's partitions from query plans.  This also controls
        the planner's ability to generate query plans which allow the query
        executor to remove (ignore) partitions during query execution.  The
        default is <literal>on</literal>.
        See <xref linkend="ddl-partition-pruning"/> for details.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-enable-partitionwise-join" xreflabel="enable_partitionwise_join">
      <term><varname>enable_partitionwise_join</varname>