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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: Alexander Lakhin <exclusion@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2024-04-23T16:20:46Z
Lists: pgsql-hackers

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Hi,

On Tue, Apr 23, 2024 at 04:59:09AM +0000, Bertrand Drouvot wrote:
> Hi,
> 
> On Mon, Apr 22, 2024 at 03:00:00PM +0300, Alexander Lakhin wrote:
> > 22.04.2024 13:52, Bertrand Drouvot wrote:
> > > 
> > > That's weird, I just launched it several times with the patch applied and I'm not
> > > able to see the seg fault (while I can see it constently failing on the master
> > > branch).
> > > 
> > > Are you 100% sure you tested it against a binary with the patch applied?
> > > 
> > 
> > Yes, at least I can't see what I'm doing wrong. Please try my
> > self-contained script attached.
> 
> Thanks for sharing your script!
> 
> Yeah your script ensures the patch is applied before the repro is executed.
> 
> I do confirm that I can also see the issue with the patch applied (but I had to
> launch multiple attempts, while on master one attempt is enough).
> 
> I'll have a look.

Please find attached v2 that should not produce the issue anymore (I launched a
lot of attempts without any issues). v1 was not strong enough as it was not
always checking for the dependent object existence. v2 now always checks if the
object still exists after the additional lock acquisition attempt while recording
the dependency.

I still need to think about v2 but in the meantime could you please also give
v2 a try on you side?

Regards,

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

Commits

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  1. Avoid orphaned objects dependencies

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