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.
A separate GUC seems kind of weird. Wouldn't it be better with something like %(format)t or such in the log_line_prefix itself in that case? That could also be expanded to other parameters, should we need them?