Re: Hard limit on WAL space used (because PANIC sucks)

On Sat, Jun 8, 2013 at 11:27 AM, Andres Freund <andres(at)2ndquadrant(dot)com>wrote:

>
> You know, the PANIC isn't there just because we like to piss of
> users. There's actual technical reasons that don't just go away by
> judging the PANIC as stupid.
> At the points where the XLogInsert()s happens we're in critical sections
> out of which we *cannot* ERROR out because we already may have made
> modifications that cannot be allowed to be performed
> partially/unlogged. That's why we're throwing a PANIC which will force a
> cluster wide restart including *NOT* writing any further buffers from
> s_b out.
>

If archiving is on and failure is due to no space, could we just keep
trying XLogFileInit again for a couple minutes to give archiving a chance
to do its things? Doing that while holding onto locks and a critical
section would be unfortunate, but if the alternative is a PANIC, it might
be acceptable.

The problem is that even if the file is only being kept so it can be
archived, once archiving succeeds I think the file is not removed
immediately but rather not until the next checkpoint, which will never
happen when the locks are still held.

Cheers,

Jeff