<primary>pg_stat_get_backend_wait_event</primary>
        </indexterm>
        <function>pg_stat_get_backend_wait_event</function> ( <type>integer</type> )
        <returnvalue>text</returnvalue>
       </para>
       <para>
        Returns the wait event name if this backend is currently waiting,
        otherwise NULL. See <xref linkend="wait-event-activity-table"/> through
        <xref linkend="wait-event-timeout-table"/>.
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <indexterm>
         <primary>pg_stat_get_backend_wait_event_type</primary>
        </indexterm>
        <function>pg_stat_get_backend_wait_event_type</function> ( <type>integer</type> )
        <returnvalue>text</returnvalue>
       </para>
       <para>
        Returns the wait event type name if this backend is currently waiting,
        otherwise NULL.  See <xref linkend="wait-event-table"/> for details.
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <indexterm>
         <primary>pg_stat_get_backend_xact_start</primary>
        </indexterm>
        <function>pg_stat_get_backend_xact_start</function> ( <type>integer</type> )
        <returnvalue>timestamp with time zone</returnvalue>
       </para>
       <para>
        Returns the time when the backend's current transaction was started.
       </para></entry>
      </row>
     </tbody>
    </tgroup>
   </table>

 </sect2>
 </sect1>

 <sect1 id="monitoring-locks">
  <title>Viewing Locks</title>

  <indexterm zone="monitoring-locks">
   <primary>lock</primary>
   <secondary>monitoring</secondary>
  </indexterm>

  <para>
   Another useful tool for monitoring database activity is the
   <structname>pg_locks</structname> system table.  It allows the
   database administrator to view information about the outstanding
   locks in the lock manager. For example, this capability can be used
   to:

   <itemizedlist>
    <listitem>
     <para>
      View all the locks currently outstanding, all the locks on
      relations in a particular database, all the locks on a
      particular relation, or all the locks held by a particular
      <productname>PostgreSQL</productname> session.
     </para>
    </listitem>

    <listitem>
     <para>
      Determine the relation in the current database with the most
      ungranted locks (which might be a source of contention among
      database clients).
     </para>
    </listitem>

    <listitem>
     <para>
      Determine the effect of lock contention on overall database
      performance, as well as the extent to which contention varies
      with overall database traffic.
     </para>
    </listitem>
   </itemizedlist>

   Details of the <structname>pg_locks</structname> view appear in
   <xref linkend="view-pg-locks"/>.
   For more information on locking and managing concurrency with
   <productname>PostgreSQL</productname>, refer to <xref linkend="mvcc"/>.
  </para>
 </sect1>

 <sect1 id="progress-reporting">
  <title>Progress Reporting</title>

  <para>
   <productname>PostgreSQL</productname> has the ability to report the progress of
   certain commands during command execution.  Currently, the only commands
   which support progress reporting are <command>ANALYZE</command>,
   <command>CLUSTER</command>,
   <command>CREATE INDEX</command>, <command>VACUUM</command>,
   <command>COPY</command>,
   and <xref linkend="protocol-replication-base-backup"/> (i.e., replication
   command that <xref linkend="app-pgbasebackup"/> issues to take
   a base backup).
   This may be expanded in the future.
  </para>

 <sect2 id="analyze-progress-reporting">
  <title>ANALYZE Progress Reporting</title>

  <indexterm>
   <primary>pg_stat_progress_analyze</primary>
  </indexterm>

  <para>
   Whenever <command>ANALYZE</command> is running, the
   <structname>pg_stat_progress_analyze</structname> view will contain a
   row for each