</informaltable>

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

consisting of two hexadecimal numbers separated by a dot. The numbers

are the process start time and the

consisting of two4-bytehexadecimal numbers separated by a dot.

The numbersare 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) || '.' ||

to_hex(pid)

regexp_replace('0000' ||to_hex(pid), '^0*(.*....)$', '\1')

FROM pg_stat_activity;

</programlisting>