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help / color / mirror / Atom feedFrom: Mihail Nikalayeu <[email protected]>
To: Amit Kapila <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Antonin Houska <[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: Thu, 30 Apr 2026 13:24:41 +0200
Message-ID: <CADzfLwWnbKcb3v8sStdgNE=WNc3uUqx5SiS4zftX2UaEfNzG5w@mail.gmail.com> (raw)
In-Reply-To: <CAA4eK1JhuT5fyTosWDZ+Pgs+j7xEjObTyRMn80uNKgi_ivqHbw@mail.gmail.com>
References: <CAA4eK1Jg21ODQ7fS2fvN5W_S5kDRhAP5inj3XMRQaa=s-GbYhw@mail.gmail.com>
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Hello!
On Mon, Apr 27, 2026 at 6:25 AM Amit Kapila <[email protected]> wrote:
> Alvaro, others, what is your take on this?
I agree with you here - we should AT LEAST make that an ERROR instead
of an assert and also check it during cache access (not only during
the scan because of cache misses).
But I think it will still be fragile in case of some extensions installed.
Anyway... We also have an issue with correctness right now.
I took the old stress test from [0] (the first two) and it fails now,
even with the fix from [1] ("Possible premature SNAPBUILD_CONSISTENT
with DB-specific running_xacts").
It looks like [1] fixes 008_repack_concurrently.pl, but
007_repack_concurrently.pl fails anyway, including
pgbench: error: client 1 script 0 aborted in command 10 query 0:
ERROR: could not create unique index "tbl_pkey_repacknew"
# DETAIL: Key (i)=(383) is duplicated.
and
'pgbench: error: pgbench:client 23 script 0 aborted in command 31
query 0: ERROR: division by zero
Last one is not MVCC-related; you can see from the logs that it
performs something like SELECT (509063) / 0 when the table sum
changes.
Setting need_shared_catalogs = true make them pass, so something is
wrong with its correctness.
P.S.
I think it is good idea to add these stress tests to the source tree,
perhaps with some kind PG_TEST_EXTRA=stress (as done in [1]).
[0]: https://www.postgresql.org/message-id/flat/CADzfLwUitd5J17O9FUxNGrZBurOpL6n%2BtnS6dgArXi-i9DNxhg%40m...
[1]: https://www.postgresql.org/message-id/flat/CAHg%2BQDcQak4jx_6X2_Ws98rzG%3DxBARLjqm_%3D56wTRUtNsY4DZQ...
[2]: https://www.postgresql.org/message-id/flat/CADzfLwWC%2BKxYWb-2QotWaz-q1LK8koLNVUR1Q8obAtt%2BR_sORA%4...
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Subject: Re: Adding REPACK [concurrently]
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