Custom timestamp format in logs

Hi all,

This week, we heard about a user willing to use a custom timestamp
format across a set of services to improve the debugability of the
whole set, Postgres being one of them. Unfortunately datestyle does
not take into account the logs. Would it be worth adding a new GUC
able to control the timestamp format in the logs?

We could still redirect the logs with syslog and have a custom
timestamp format there, but in the case of this particular user syslog
was a no-go. Looking at the code, timestamp format is now hardcoded in
setup_formatted_log_time and setup_formatted_start_time when calling
pg_strftime @ elog.c, so it doesn't seem to be much complicated to do.

Opinions? This thread is here for that.
Regards,
-- 
Michael