Re: Race conditions in logical decoding - Mailing list pgsql-hackers

From Andres Freund
Subject Re: Race conditions in logical decoding
Date
Msg-id 5k2dfckyp6zv2fiovosvtbya5onvplgviz5n4kdamxupff4vi2@yytzfnwr2ox7
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In response to Re: Race conditions in logical decoding  (Antonin Houska <ah@cybertec.at>)
Responses Re: Race conditions in logical decoding
Re: Race conditions in logical decoding
List pgsql-hackers
Hi,

On 2026-01-20 09:30:33 +0100, Antonin Houska wrote:
> Antonin Houska <ah@cybertec.at> wrote:
> 
> > I'm not sure yet how to fix the problem. I tried to call XactLockTableWait()
> > from SnapBuildAddCommittedTxn() (like it happens in SnapBuildWaitSnapshot()),
> > but it made at least one regression test (subscription/t/010_truncate.pl)
> > stuck - probably a deadlock. I can spend more time on it, but maybe someone
> > can come up with a good idea sooner than me.
> 
> Attached here is what I consider a possible fix - simply wait for the CLOG
> update before building a new snapshot.

I don't think that's enough - during non-timetravel visibility semantics, you
can only look at the clog if the transaction isn't marked as in-progress in
the procarray.  ISTM that we need to do that here too?

Greetings,

Andres



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