Horton

Re: Fix bug with accessing to temporary tables of other sessions

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Daniil Davydov <3danissimo@gmail.com>, Jim Jones <jim.jones@uni-muenster.de>, Soumya S Murali <soumyamurali.work@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Stepan Neretin <slpmcf@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Mohamed Ali <moali.pg@gmail.com>, Nazneen Jafri <jafrinazneen@gmail.com>, Shawn McCoy <shawn.the.mccoy@gmail.com>
Date: 2026-05-08T06:39:09Z
Lists: pgsql-hackers 
On Fri, May 8, 2026 at 9:19 AM Michael Paquier <michael@paquier.xyz> wrote:
> On Thu, May 07, 2026 at 11:04:16AM +0300, Alexander Korotkov wrote:
> > Let me do a quick summary:
> >  * Our buffer manager is not capable for reading temp tables of other sessions.
> >  * This was covered by explicit checks, but broken since b7b0f3f27241
> > introduced alternative code path for reading tables.
> >  * This doesn't apply to DROP TABLE.  DROP TABLE is a conscious
> > exclusion and the only operation we can do correctly for other
> > session' temp tables.  There is an explicit exclusion in the code to
> > skip the attempt to cleanup buffers of other session' temp tables.
> >  * This patchset consists of tests (0001) for various operations with
> > other session's temp tables including buggy behavior, and the fix
> > (0002) including changes for tests.
> >
> > Thus, I don't see the reason why this shouldn't be committed and
> > backpatched to PG17 (first release containing b7b0f3f27241).
> > Opinions?  Michael?
>
> Hmm.  I don't have any counter-arguments against a backpatch based on
> your argument related to b7b0f3f27241.  Thanks for reorganizing the
> patch set so as the tests happen first, and the changes in the code
> become second.
>
> If you wish me to look at this patch set in details, I may be able to
> do so around the beginning of next week.  I'm not sure that there is a
> strong urgency in tackling this issue for this minor release, this
> could wait a bit more..

Absolutely, no urgency to include it into this minor release as I
already agreed [1].  You're very welcome if you could take a look in
the beginning of the next week.

Links.
1. https://www.postgresql.org/message-id/CAPpHfdsEr6RF-SkzVGD6PzFusENbpNPxKnRY7iQQ%3DcZQYJia6w%40mail.gmail.com

------
Regards,
Alexander Korotkov
Supabase