From: Antonin Houska <ah@cybertec.at>
To: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
cc: Alvaro Herrera <alvherre@alvh.no-ip.org>,
    Pg Hackers <pgsql-hackers@lists.postgresql.org>,
    Robert Treat <rob@xzilla.net>, Fujii Masao <masao.fujii@gmail.com>
Subject: Re: Adding REPACK [concurrently]
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Comments: In-reply-to Mihail Nikalayeu <mihailnikalayeu@gmail.com>
   message dated "Mon, 01 Sep 2025 11:06:35 +0200."
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Date: Mon, 01 Sep 2025 17:30:18 +0200
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Mihail Nikalayeu <mihailnikalayeu@gmail.com> wrote:

> Antonin Houska <ah@cybertec.at>:
> > Are you sure the test is complete? I see no occurrence of the REPACK c=
ommand
> > in it.
> Oops, send invalid file. The correct one in attachment.

Thanks!

The problem was that when removing the original "preserve visibility patch=
"
v12-0005 [1] from the series, I forgot to change the value of
'need_full_snapshot' argument of CreateInitDecodingContext().

v12 and earlier treated the repacked table like system catalog, so it was
o.k. to pass need_full_snapshot=3Dfalse. However, it must be true now, oth=
erwise
the snapshot created for the initial copy does not see commits of transact=
ions
that do not change regular catalogs.

The fix is as simple as

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/rep=
lication/logical/snapbuild.c
index f481a3cec6d..7866ac01278 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -502,6 +502,7 @@ SnapBuildInitialSnapshotForRepack(SnapBuild *builder)
        StringInfo      buf =3D makeStringInfo();
 =

        Assert(builder->state =3D=3D SNAPBUILD_CONSISTENT);
+       Assert(builder->building_full_snapshot);
 =

        snap =3D SnapBuildBuildSnapshot(builder);
 =


I'll apply it to the next version of the "Add CONCURRENTLY option to REPAC=
K
command" patch.


[1] https://www.postgresql.org/message-id/flat/CAFj8pRDK89FtY_yyGw7-MW-zTa=
HOCY4m6qfLRittdoPocz+dMQ@mail.gmail.com

-- =

Antonin Houska
Web: https://www.cybertec-postgresql.com