Re: Idea: recycle WAL segments, don't delete/recreate 'em

Patrick Macdonald <patrickm(at)redhat(dot)com> writes:
> Well, notion and actual practice can be mutually exclusive. Your
> initial message stated that you would like to rename the log segment.
> This insinuated that the log segment was not moved. Therefore, a
> straight rename would cause problems with the future point-in-time
> recovery item (ie. the only existing version of log segment N has
> been renamed to N+5). A backup of the database could not roll forward
> through this name change as stated. That was my objection.

I think you are missing the point completely. The rename will occur
only at the time when we would otherwise DELETE the old log segment.
If, for PIT or any other purpose, we do not wish to delete a log
segment, then it's not going to get recycled either. My proposal is
then when, and only when, we are prepared to discard an old log segment
forever, we instead rename it to be a created-in-advance future log
segment.

What you may really be saying is that the existing scheme for management
of log segments is inappropriate for PIT usage; if so feel free to
propose a better one. But I don't see how recycling of no-longer-wanted
segments can break anything.

regards, tom lane