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Re: Avoid orphaned objects dependencies, take 3

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Robert Haas <robertmhaas@gmail.com>, Roman Eskin <r.eskin@arenadata.io>, Michael Paquier <michael@paquier.xyz>, Alexander Lakhin <exclusion@gmail.com>, pgsql-hackers@lists.postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2026-06-05T13:12:34Z
Lists: pgsql-hackers 
Hi,

On Thu, Jun 04, 2026 at 10:17:57AM -0700, Jeff Davis wrote:
> Given that we don't do another name lookup, the object Oid doesn't
> change, and it's not obvious why we need a loop in this path.
> 
> A sequence like:
> 
> Earlier during DDL processing:
>   0. Name lookup and ACL check (and track ACLs)
> 
> When recording dependencies:
>   1. Lock object
>   2. Check that it still exists, error if not
>   3. recheck tracked ACLs, error if failure
> 
> could work too, right?

Yeah, that's a good point, thanks!

> I see why you might want to do the checks while not holding the lock,
> but it doesn't seem like a requirement (if the user doesn't have
> permissions it should fail quickly and release).

I agree that we can get rid of the loop and that's what v24 shared up-thread [1]
is now implementing. The downside is that one could take a lock on an object
he has no privileges on but then, as you said, it will be released shortly after.

[1]: https://postgr.es/m/aiLKkTC6QBt8i35P%40bdtpg

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

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  1. Avoid orphaned objects dependencies

  2. Don't try to record dependency on a dropped column's datatype