From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
---|---|
To: | "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com> |
Cc: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>, Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, Nitin Motiani <nitinmotiani(at)google(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
Subject: | Re: long-standing data loss bug in initial sync of logical replication |
Date: | 2025-03-15 06:24:40 |
Message-ID: | CAA4eK1KKX74B_hitfpK3-R4kAx5qJ6X71OeGxW7cvjO5qOV1ZQ@mail.gmail.com |
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On Thu, Mar 13, 2025 at 2:12 PM Hayato Kuroda (Fujitsu)
<kuroda(dot)hayato(at)fujitsu(dot)com> wrote:
>
>
> Workload C. DDL is happening on publication but on unrelated table
> ============================================
> We did not run the workload because we expected this could be same results as D.
> 588acf6 is needed to optimize the workload.
>
> -----
>
> Workload D. DDL is happening on the related published table,
> and one insert is done per invalidation
> =========================================
> This workload had huge regression same as the master branch. This is expected
> because distributed invalidation messages require all concurrent transactions
> to rebuild relsync caches.
>
> Concurrent txn | Head (sec) | Patch (sec) | Degradation (%)
> ------------------ | ------------ | ------------ | ----------------
> 50 | 0.013496 | 0.015588 | 15.5034
> 100 | 0.015112 | 0.018868 | 24.8517
> 500 | 0.018483 | 0.038714 | 109.4536
> 1000 | 0.023402 | 0.063735 | 172.3524
> 2000 | 0.031596 | 0.110860 | 250.8720
>
IIUC, workloads C and D will have regression in back branches, and
HEAD will have regression only for workload D. We have avoided
workload C regression in HEAD via commits 7c99dc587a and 3abe9dc188.
We can backpatch those commits if required, but I think it is better
not to do those as scenarios C and D won't be that common, and we
should go ahead with the fix as it is. In the future, if we get any
way to avoid regression due to scenario-D, then we can do that for the
HEAD branch.
Thoughts?
--
With Regards,
Amit Kapila.
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