apply worker if this process
       is a parallel apply worker.  <literal>NULL</literal> indicates that this
       process is a parallel group leader or leader apply worker, or does not
       participate in any parallel operation.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>usesysid</structfield> <type>oid</type>
      </para>
      <para>
       OID of the user logged into this backend
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>usename</structfield> <type>name</type>
      </para>
      <para>
       Name of the user logged into this backend
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>application_name</structfield> <type>text</type>
      </para>
      <para>
       Name of the application that is connected
       to this backend
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>client_addr</structfield> <type>inet</type>
      </para>
      <para>
       IP address of the client connected to this backend.
       If this field is null, it indicates either that the client is
       connected via a Unix socket on the server machine or that this is an
       internal process such as autovacuum.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>client_hostname</structfield> <type>text</type>
      </para>
      <para>
       Host name of the connected client, as reported by a
       reverse DNS lookup of <structfield>client_addr</structfield>. This field will
       only be non-null for IP connections, and only when <xref linkend="guc-log-hostname"/> is enabled.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>client_port</structfield> <type>integer</type>
      </para>
      <para>
       TCP port number that the client is using for communication
       with this backend, or <literal>-1</literal> if a Unix socket is used.
       If this field is null, it indicates that this is an internal server process.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>backend_start</structfield> <type>timestamp with time zone</type>
      </para>
      <para>
       Time when this process was started.  For client backends,
       this is the time the client connected to the server.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>xact_start</structfield> <type>timestamp with time zone</type>
      </para>
      <para>
       Time when this process' current transaction was started, or null
       if no transaction is active. If the current
       query is the first of its transaction, this column is equal to the
       <structfield>query_start</structfield> column.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>query_start</structfield> <type>timestamp with time zone</type>
      </para>
      <para>
       Time when the currently active query was started, or if
       <structfield>state</structfield> is not <literal>active</literal>, when the last query
       was started
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>state_change</structfield> <type>timestamp with time zone</type>
      </para>
      <para>
       Time when the <structfield>state</structfield> was last changed
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para