</informaltable>

The <literal>%c</> escape prints a quasi-unique session identifier,

consisting of two 4-byte hexadecimal numbersseparated by a dot.

The numbers are the process start time and the

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. For example, to generate the session

identifier from <literal>pg_stat_activity</>, use this query:

<programlisting>

SELECT to_hex(EXTRACT(EPOCH FROM backend_start)::integer) || '.' ||

regexp_replace('0000' || '0133e3', '^0*(.{4,})$', '\1')

to_hex(pid)

FROM pg_stat_activity;

</programlisting>

</para>

</listitem>

<listitem>

<para>

Have <quote>session id</> (<literal>%c</>) in <link

linkend="guc-log-line-prefix"><varname>log_line_prefix</></link>

always output at least four hex digits after the period (Bruce Momjian)

</para>

</listitem>

</itemizedlist>

</sect3>

}

break;

case'c':

appendStringInfo(buf,"%lx.%04x", (long) (MyStartTime),MyProcPid);

appendStringInfo(buf,"%lx.%x", (long) (MyStartTime),MyProcPid);

break;

case'p':

appendStringInfo(buf,"%d",MyProcPid);

appendStringInfoChar(&buf,',');

appendStringInfo(&buf,"%lx.%04x", (long)MyStartTime,MyProcPid);

appendStringInfo(&buf,"%lx.%x", (long)MyStartTime,MyProcPid);

appendStringInfoChar(&buf,',');