Re: BUG #17103: WAL segments are not removed after exceeding max_slot_wal_keep_size

At Wed, 14 Jul 2021 19:10:26 -0400, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote in
> On Tue, Jul 13, 2021 at 10:12 PM Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>
> wrote:
> > Useless WAL files will be removd after a checkpoint runs.
> >
>
> They should be, but they are not. That is the bug. They just hang
> around, checkpoint after checkpoint. Some of them do get cleaned up, to
> make up for new ones created during that cycle. It treats
> max_slot_wal_keep the same way it treats wal_keep_size (but only if a
> "lost" slot is hanging around). If you drop the lost slot, only then does
> it remove all the accumulated WAL at the next checkpoint.

Thanks! I saw the issue here. Some investigation showd me a doubious
motion of XLogCtl->repliationSlotMinLSN. Slot invalidation is
forgetting to recalculate it and that misbehavior retreats the segment
horizon.

So the attached worked for me. I'll repost the polished version
including test.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center