-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.217 2009/06/02 17:37:55 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.218 2009/06/03 00:38:34 momjian Exp $ -->
<chapter Id="runtime-config">
<title>Server Configuration</title>
consisting of two 4-byte hexadecimal numbers (without leading zeros)
separated by a dot. The numbers are the process start time and the
process ID, so <literal>%c</> can also be used as a space saving way
- of printing those items.
+ of printing those items. For example, to generate the session
+ identifier from <literal>pg_stat_activity</>, use:
+<programlisting>
+SELECT to_hex(EXTRACT(EPOCH FROM backend_start)::integer) || '.' ||
+ to_hex(procpid)
+FROM pg_stat_activity;
+</programlisting>
+
</para>
<tip>