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help / color / mirror / Atom feedFrom: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: shihao zhong <zhong950419@gmail.com>
Cc: Jim Jones <jim.jones@uni-muenster.de>
Cc: pgsql-hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Add a permission check to pg_stat_get_backend_subxact()
Date: Tue, 22 Sep 2026 14:03:02 +0000
Message-ID: <arKKltvf8PpIByOF@bdtpg> (raw)
In-Reply-To: <arJlSpeSs8yPKipu@paquier.xyz>
References: <ef48668c-cf8e-4f4b-bf39-4b3b9fb9b85a@uni-muenster.de>
<aqOzYr0It5sP7eFF@paquier.xyz>
<c7a0be5d-5328-41dd-a7bf-6b964e9f7a06@uni-muenster.de>
<aqSXMjhwFFzz_zyo@paquier.xyz>
<CAGRkXqRGVNvvkY7a7X=3Bn=WgfLuFZ5iVsBf+t6HSfm2RwVC+g@mail.gmail.com>
<aqec3MF_GDsMdadl@paquier.xyz>
<arD/w47Ug1GaObfq@bdtpg>
<arJJVOo1mOKvK8US@paquier.xyz>
<arJSXjs6szWXIr0H@bdtpg>
<arJlSpeSs8yPKipu@paquier.xyz>
Hi,
On Tue, Sep 22, 2026 at 08:23:54PM +0900, Michael Paquier wrote:
> On Tue, Sep 22, 2026 at 10:03:10AM +0000, Bertrand Drouvot wrote:
> > I'm not sure the user ID alone is enough though: if B reuses A's ProcNumber,
> > pg_stat_get_backend_wal(B_pid) could still return A's cached statistics when
> > the caller is allowed to see A's data.
> >
> > I'd keep the PID check from 0002 as well. A generation would be more robust
> > against PID reuse, as done for example for AIO handles, but introducing a
> > backend generation seems like too much for this case.
> >
> > So storing both seems like the simplest approach: the user ID for the ACL
> > check and the PID for matching the statistics to the requested backend.
>
> The PID would also act as a kind of weaker generation number, slightly
> weaker but simpler. So that works here. Perhaps you would like to
> give it a shot?
Do you mean adding the user ID on top of Shihao's 0002? If so, I can have a look,
unless Shihao is already planning to update the patch along those lines?
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
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To: pgsql-hackers@postgresql.org
Cc: bertranddrouvot.pg@gmail.com, michael@paquier.xyz, zhong950419@gmail.com, jim.jones@uni-muenster.de, pgsql-hackers@lists.postgresql.org
Subject: Re: Add a permission check to pg_stat_get_backend_subxact()
In-Reply-To: <arKKltvf8PpIByOF@bdtpg>
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