Re: long-standing data loss bug in initial sync of logical replication

From: Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com>
To: "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>
Cc: Masahiko Sawada <sawada(dot)mshk(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>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Subject: Re: long-standing data loss bug in initial sync of logical replication
Date: 2024-10-04 07:22:51
Message-ID: CANhcyEWiq2PNkKUQdd0e3OyFqVYjgwkCaE6n32=-+Yt7rVT_Ew@mail.gmail.com
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Hi Kuroda-san,

Thanks for reviewing the patch.
>
> 1.
> I feel the name of SnapBuildDistributeNewCatalogSnapshot() should be updated because it
> distributes two objects: catalog snapshot and invalidation messages. Do you have good one
> in your mind? I considered "SnapBuildDistributeNewCatalogSnapshotAndInValidations" or
> "SnapBuildDistributeItems" but seems not good :-(.

I have renamed the function to 'SnapBuildDistributeSnapshotAndInval'. Thoughts?

> 2.
> Hmm, still, it is overengineering for me to add a new type of invalidation message
> only for the publication. According to the ExecRenameStmt() we can implement an
> arbitrary rename function like RenameConstraint() and RenameDatabase().
> Regaring the ALTER PUBLICATION OWNER TO, I feel adding CacheInvalidateRelcacheAll()
> and InvalidatePublicationRels() is enough.

I agree with you.

>
> I attached a PoC which implements above. It could pass tests on my env. Could you
> please see it tell me how you think?

I have tested the POC and it is working as expected. The changes look
fine to me. I have created a patch for the same.
Currently, we are passing 'PUBLICATION_PART_ALL' as an argument to
function 'GetPublicationRelations' and
'GetAllSchemaPublicationRelations'. Need to check if we can use
'PUBLICATION_PART_ROOT' or 'PUBLICATION_PART_LEAF' depending on the
'publish_via_partition_root' option. Will test and address this in the
next version of the patch. For now, I have added a TODO.

Thanks and Regards,
Shlok Kyal

Attachment Content-Type Size
v12-0001-Distribute-invalidatons-if-change-in-catalog-tab.patch application/octet-stream 13.9 KB
v12-0002-Selective-Invalidation-of-Cache.patch application/octet-stream 7.0 KB

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