From: | Michael Paquier <michael(at)paquier(dot)xyz> |
---|---|
To: | Bertrand Drouvot <bertranddrouvot(dot)pg(at)gmail(dot)com> |
Cc: | pgsql-hackers(at)lists(dot)postgresql(dot)org |
Subject: | Re: Spurious pgstat_drop_replslot() call |
Date: | 2024-03-11 07:15:40 |
Message-ID: | Ze6vnAV8qNTJAa_F@paquier.xyz |
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Lists: | pgsql-hackers |
On Fri, Mar 08, 2024 at 03:04:10PM +0000, Bertrand Drouvot wrote:
> The switch in the patch from "drop" to "invalidation" is in [1], see:
>
> "
> Given the precedent of max_slot_wal_keep_size, I think it's wrong to
just drop
> the logical slots. Instead we should just mark them as
invalid,
> like InvalidateObsoleteReplicationSlots().
>
> Makes fully sense and done that way in the attached patch.
> “
>
> But yeah, hard to be sure why this call is there, at least I don't remember...
Yep, noticed that on Friday.
> We can not be 100% sure that the stats are up to date when the process holding
> the active slot is killed.
>
> So v2 attached adds a test where we ensure first that we have non empty stats
> before triggering the invalidation.
Ah, that explains the extra poll. What you have done here makes sense
to me, and the new test fails immediately if I add back the stats drop
in the invalidation code path.
That's a slight change in behavior, unfortunately, and it cannot be
called a bug as this improves the visibility of the stats after an
invalidation, so this is not something that can be backpatched.
--
Michael
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