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Re: Avoid orphaned objects dependencies, take 3

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Alexander Lakhin <exclusion@gmail.com>, pgsql-hackers@lists.postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2024-06-13T18:27:45Z
Lists: pgsql-hackers 
On Thu, Jun 13, 2024 at 12:52 PM Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:
> > > table_open(childRelId, ...) would lock any "ALTER TABLE <childRelId> DROP CONSTRAINT"
> > > already. Not sure I understand your concern here.
> >
> > I believe this is not true. This would take a lock on the table, not
> > the constraint itself.
>
> I agree that it would not lock the constraint itself. What I meant to say is that
> , nevertheless, the constraint can not be dropped. Indeed, the "ALTER TABLE"
> necessary to drop the constraint (ALTER TABLE <childRelId> DROP CONSTRAINT) would
> be locked by the table_open(childRelId, ...).

Ah, right. So, I was assuming that, with either this version of your
patch or the earlier version, we'd end up locking the constraint
itself. Was I wrong about that?

-- 
Robert Haas
EDB: http://www.enterprisedb.com

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  1. Avoid orphaned objects dependencies

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