Re: BUG #17804: Assertion failed in pg_stat after fetching from pg_stat_database and switching cache->snapshot

At Fri, 28 Apr 2023 15:48:16 +0900, Michael Paquier <michael(at)paquier(dot)xyz> wrote in
> On Fri, Apr 28, 2023 at 03:04:04PM +0900, Kyotaro Horiguchi wrote:
> > Just I wanted not to do that much in the guc callback including memory
> > context operations. If it is compeltly safe, I don't object just
> > clearing snapshots in the callback.
>
> I vaguely recalled some memory context deletions done in one of the
> assign callbacks, like the one for the plan resets, but it doesn't
> seem to be the case, looking closely.. Hm.

For the the record, I'm not saying that it is dangerous to clear
snapshots directly in the callback. In fact, as I mentioned earlier, I
believe there is no issue with that. But, I believe it is simpler
that the actual work is separate from the callback path since we don't
need to worry about when the guc-callback will be called.

Regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center