Re: log_filename_prefix --> log_filename + strftime()

"Ed L." <pgsql(at)bluepolka(dot)net> writes:
> Consider the case if one is
> truncating logs on rotation and rotating hourly. UTC vs local is
> irrelevant. If local time shifts backward from 02:00 to 01:00, our UTC
> offset will move in the negative direction. If 1) our policy were to
> truncate on rotation, and 2) we were rotating hourly or more frequently,
> and 3) our filename would be identical the 2nd time through that clock hour
> (i.e., it did not contain the epoch or UTC offset), this could cause a log
> file rotation into the same filename we just had open, thereby erasing an
> hour of log data. Apache's rotatelogs apparently has the same issue
> without a solution, and warns of it in the code.

Hmm. Maybe we should remember the previous filename, and only truncate
when the new one is different (plus all the other conditions); else append.

regards, tom lane