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From: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sat, 10 Jan 2026 20:37:06 +0300
Message-ID: <CADzfLwU-OmxW3t3AoQo9=K7uq4G1yZ-txcetzW3jbcVxV_pJew@mail.gmail.com>
Subject: Re: Adding REPACK [concurrently]
To: Antonin Houska <ah@cybertec.at>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, 
	Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
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Hello, Antonin!

On Thu, Jan 8, 2026 at 7:59=E2=80=AFPM Antonin Houska <ah@cybertec.at> wrot=
e:
> v29 tries to fix the problem.

Some comments for 0001-0004.

------ 0001 -----

> src/bin/scripts/t/103_repackdb.pl:1:
>  # Copyright (c) 2021-2025

Update year for 2026.

> * FIXME: this is missing a way to specify the index to use to repack one
> * table, or whether to pass a WITH INDEX clause when multiple tables are
> * used.  Something like --index[=3Dindexname].  Adding that bleeds into
> * vacuuming.c as well.

Comments look stale.

> return "???";
I think it is better to add Assert(false); before (done that way in a
few places).

> command <link linkend=3D"sql-repack"><command>REPACK</command></link> The=
re
need .

> =E2=80=9CAn utility=E2=80=9D
Should be =E2=80=9CA utility=E2=80=9D

> else if (pg_strcasecmp(cmd, "CLUSTER") =3D=3D 0)
>    cmdtype =3D PROGRESS_COMMAND_CLUSTER;

Should we set PROGRESS_COMMAND_REPACK here? Because cluster is not
used anywhere. Probably we may even delete PROGRESS_COMMAND_CLUSTER.

> CLUOPT_RECHECK_ISCLUSTERED
It is not set anymore... Probably something is wrong here or we need
to just remove that constant and check for it.

------ 0002 -----

> rebuild_relation(Relation OldHeap, Relation index, bool verbose)
It removes unused cmd parameter, but I think it is better to not add
it in the previous commit.

------ 0003 -----

> int       newxcnt =3D 0;

I think it is better to use uint32 for consistency here.

Also, I think it is worth adding Assert(snapshot->snapshot_type =3D=3D
SNAPSHOT_HISTORIC_MVCC)

------ 0004 -----

> /* Is REPACK (CONCURRENTLY) being run by this backend? */
> if (am_decoding_for_repack())

We should check change_useless_for_repack here - to avoid looking and
TRUNCATE of unrelated tables.

> /* For the same reason, unlock TOAST relation. */
> if (OldHeap->rd_rel->reltoastrelid)
>    LockRelationOid(OldHeap->rd_rel->reltoastrelid, AccessExclusiveLock);

Hm, we are locking here instead of unlocking ;)

> (errhint("Relation \"%s\" has no identity index.",
>       RelationGetRelationName(rel)))));

One level of braces may be removed.

> * to decode on behalf of REPACK (CONCURRENT)?

CONCURRENTLY

> * If recheck is required, it must have been preformed on the source

"performed"

> * On exit,'*scan_p' contains the scan descriptor used. The caller must cl=
ose
> * it when he no longer needs the tuple returned.

There is no scan_p argument here.

> * Copyright (c) 2012-2025, PostgreSQL Global Development Group

2026

> newtuple =3D change->data.tp.newtuple !=3D NULL ?
>   change->data.tp.newtuple : NULL;

> oldtuple =3D change->data.tp.oldtuple !=3D NULL ?
>    change->data.tp.oldtuple : NULL;
> newtuple =3D change->data.tp.newtuple !=3D NULL ?
>    change->data.tp.newtuple : NULL;

Hm, should it be just x =3D y ?

> apply_concurrent_insert

Double newline at function start.

> heap2_decode

Should we check for change_useless_for_repack here also? (for multi
insert, for example).

Best regards,
Mikhail.