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help / color / mirror / Atom feedFrom: Mihail Nikalayeu <[email protected]>
To: Andres Freund <[email protected]>
Cc: Antonin Houska <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: Srinath Reddy Sadipiralla <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: Pg Hackers <[email protected]>
Cc: Robert Treat <[email protected]>
Subject: Re: Adding REPACK [concurrently]
Date: Tue, 14 Apr 2026 18:55:17 +0200
Message-ID: <CADzfLwU8Qw6LXFHO7Tbjc-O7o+tM26jdnOJBWqYLu61rf7bO+g@mail.gmail.com> (raw)
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Hello!
On Tue, Apr 14, 2026 at 3:58 PM Andres Freund <[email protected]> wrote:
> I still think this needs to be in the deadlock detector. The lock cycle just
> needs to be a bit more complicated for a hack in JoinWaitQueue not to work.
> There's no guarantee that the wait that triggers the deadlock is actually on
> the relation being repacked.
I have started prototyping a way to declare a "future" lock which the
deadlock detector treats as a hard edge.
But I currently stuck on issues related to the fact that SUE doesn't
force weak locks (fast-path) to go through
FastPathTransferRelationLocks, so the deadlock detector can't handle
the case when another backend tries to execute LOCK TABLE repack_test
IN SHARE UPDATE EXCLUSIVE MODE;
Also, VACUUM takes the same lock.
I'm not sure how to deal with this in a non-hacky way. One option is
to force SUE to transfer locks if relation it is trying to lock
relation which marked with "future lock". But I am not sure it is good
enough or covers all tricky cases (multiple backends in the loop).
Best regards,
Mikhail.
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Subject: Re: Adding REPACK [concurrently]
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