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From: Mahendra Singh Thalor <mahi6run@gmail.com>
Date: Mon, 16 Mar 2026 23:25:22 +0530
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 <CAKYtNApC1HzL_7g2FvkqWpCGTfv+MoUzn5TmsiC90o7pftdUZg@mail.gmail.com>
Subject: Re: Adding REPACK [concurrently]
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Robert Treat <rob@xzilla.net>,
 Matthias van de Meent <boekewurm+postgres@gmail.com>,
	Antonin Houska <ah@cybertec.at>,
 Mihail Nikalayeu <mihailnikalayeu@gmail.com>,
	Pg Hackers <pgsql-hackers@lists.postgresql.org>
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On Mon, 16 Mar 2026 at 21:33, Alvaro Herrera <alvherre@alvh.no-ip.org>
wrote:
>
> On 2026-Mar-16, Robert Treat wrote:
>
> > I'm never excited about adding GUCs, but at first thought this seems
> > like a decent work-around; most people are unlikely to run multiple
> > repack concurrently's, but they can if needed. (I think the most
> > likely use case is on clusters using the "database per customer"
> > pattern, but if we have the guc, people will have a means to deal with
> > it).
>
> I wonder if, longer term, it would make sense to do away with the
> max_replication_slots GUC (and this new one) altogether, and use dynamic
> shared memory for slots instead.  There's of course always the danger
> that people would accumulate arbitrary numbers of slots since they would
> never be forced to check.  But that may be a lesser problem than having
> to gauge these GUCs with any care.
>
> --
> =C3=81lvaro Herrera               48=C2=B001'N 7=C2=B057'E  =E2=80=94
https://www.EnterpriseDB.com/
> "You're _really_ hosed if the person doing the hiring doesn't understand
> relational systems: you end up with a whole raft of programmers, none of
> whom has had a Date with the clue stick."              (Andrew Sullivan)
> https://postgr.es/m/20050809113420.GD2768@phlogiston.dyndns.org
>
>

Hi all,
I was reading this thread and was doing some tests.

postgres=3D# create table test1(a int);
CREATE TABLE
postgres=3D# create table test2(a int);
CREATE TABLE
postgres=3D# *vacuum full test1 , test2;*
VACUUM
postgres=3D# repack test1;
REPACK
postgres=3D# repack test2;
REPACK
postgres=3D#* repack test1, test2;*
ERROR:  syntax error at or near ","
LINE 1: repack test1, test2;
                    ^

I was not expecting any error but maybe I am missing something (some patch
needs to be applied to test this query?).

Thanks and Regards
Mahendra

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<div dir=3D"ltr">On Mon, 16 Mar 2026 at 21:33, Alvaro Herrera &lt;<a href=
=3D"mailto:alvherre@alvh.no-ip.org">alvherre@alvh.no-ip.org</a>&gt; wrote:<=
br>&gt;<br>&gt; On 2026-Mar-16, Robert Treat wrote:<br>&gt;<br>&gt; &gt; I&=
#39;m never excited about adding GUCs, but at first thought this seems<br>&=
gt; &gt; like a decent work-around; most people are unlikely to run multipl=
e<br>&gt; &gt; repack concurrently&#39;s, but they can if needed. (I think =
the most<br>&gt; &gt; likely use case is on clusters using the &quot;databa=
se per customer&quot;<br>&gt; &gt; pattern, but if we have the guc, people =
will have a means to deal with<br>&gt; &gt; it).<br>&gt;<br>&gt; I wonder i=
f, longer term, it would make sense to do away with the<br>&gt; max_replica=
tion_slots GUC (and this new one) altogether, and use dynamic<br>&gt; share=
d memory for slots instead.=C2=A0 There&#39;s of course always the danger<b=
r>&gt; that people would accumulate arbitrary numbers of slots since they w=
ould<br>&gt; never be forced to check.=C2=A0 But that may be a lesser probl=
em than having<br>&gt; to gauge these GUCs with any care.<br>&gt;<br>&gt; -=
-<br>&gt; =C3=81lvaro Herrera =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 48=C2=B001&#39;N 7=C2=B057&#39;E =C2=A0=E2=80=94 =C2=A0<a href=3D"https=
://www.EnterpriseDB.com/">https://www.EnterpriseDB.com/</a><br>&gt; &quot;Y=
ou&#39;re _really_ hosed if the person doing the hiring doesn&#39;t underst=
and<br>&gt; relational systems: you end up with a whole raft of programmers=
, none of<br>&gt; whom has had a Date with the clue stick.&quot; =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0(Andrew Sullivan)<br>&gt; <a href=3D"=
https://postgr.es/m/20050809113420.GD2768@phlogiston.dyndns.org">https://po=
stgr.es/m/20050809113420.GD2768@phlogiston.dyndns.org</a><br>&gt;<br>&gt;<b=
r><br>Hi all,<br>I was reading this thread and was doing some tests.<br><br=
>postgres=3D# create table test1(a int);<br>CREATE TABLE<br>postgres=3D# cr=
eate table test2(a int);<br>CREATE TABLE<br>postgres=3D# <b>vacuum full tes=
t1 , test2;</b><br>VACUUM<br>postgres=3D# repack test1;<br>REPACK<br>postgr=
es=3D# repack test2;<br>REPACK<br>postgres=3D#<b> repack test1, test2;</b><=
br>ERROR: =C2=A0syntax error at or near &quot;,&quot;<br>LINE 1: repack tes=
t1, test2;<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 ^<div><br>I was not expecting any error but maybe I am missing s=
omething (some patch needs to be applied to test this query?).<br><div><br>=
<div>Thanks and Regards<br>Mahendra</div></div></div></div>

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