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From: Kirill Reshke <reshkekirill@gmail.com>
Date: Sat, 20 Dec 2025 16:37:57 +0500
Message-ID: 
 <CALdSSPgj0+Bp0DujZmsX-xVq=k85E2OXNsvKqoak8EU7xpFVYA@mail.gmail.com>
Subject: Re: Add SPLIT PARTITION/MERGE PARTITIONS commands
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: jian he <jian.universality@gmail.com>, zengman <zengman@halodbtech.com>,
	pgsql-hackers <pgsql-hackers@lists.postgresql.org>
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 <https://www.postgresql.org/message-id/CALdSSPgj0%2BBp0DujZmsX-xVq%3Dk85E2OXNsvKqoak8EU7xpFVYA%40mail.gmail.com>
Precedence: bulk

On Sat, 20 Dec 2025 at 16:27, Alexander Korotkov <aekorotkov@gmail.com> wro=
te:
>
> On Sat, Dec 20, 2025 at 1:15=E2=80=AFPM jian he <jian.universality@gmail.=
com> wrote:
> > On Sat, Dec 20, 2025 at 6:42=E2=80=AFPM Alexander Korotkov <aekorotkov@=
gmail.com> wrote:
> > >
> > > Hi Kirill!
> >
> > > > reshke=3D# alter table only z merge partitions (z_1,z_2) into z_12;
> > > > ALTER TABLE
> > > > reshke=3D#
> > > >
> > > > ```
> > > >
> > > > IMO "alter table only ... merge partitions" does not make perfect
> > > > sense and should be rejected rather than executed. WDYT?
> > >
> > > Could you, please, clarify your point? I didn't quite get it.  It
> > > looks like pretty basic example of merging two adjacent partitions.
> > >
> >
> > > reshke=3D# alter table only z merge partitions (z_1,z_2) into z_12;
> > I think it should fail, because we are not applying to table "z" itself=
,
> > For Split/Merge partitions, we are processing the whole partitioned
> > table z hierarchy.
> >
> > alter table z merge partitions (z_1,z_2) into z_12;
> > should work.
> >
> > I guess the attached maybe is what Krill wants.


Jian, Thank, you got me right. Your patch is addressing the problem I
talk about, yes. The only issue about your patch is the actual error
message (error hint is exactly on point.)

So, instead of

```
+ERROR:  ALTER TABLE MERGE PARTITIONS must apply to child tables too
+HINT:  Do not specify the ONLY keyword.
``

I would prefer (something like)

```
+ERROR:  ALTER TABLE MERGE PARTITIONS is a non-recursive command.
+HINT:  Do not specify the ONLY keyword.
``

On Sat, 20 Dec 2025 at 16:27, Alexander Korotkov <aekorotkov@gmail.com> wro=
te:

>  I don't think the problem with ONLY keyword is
> that MERGE/SPLIT must be always recursive.  I think opposite, it's
> always non-recursive and this is why ONLY is meaningless.  Otherwise,
> we may decide to just leave it as it allowing ONLY.

+1


--=20
Best regards,
Kirill Reshke