Re: Logical Replication of sequences

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>
Cc: Alexander Lakhin <exclusion(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com>, Nathan Bossart <nathandbossart(at)gmail(dot)com>, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>, shveta malik <shveta(dot)malik(at)gmail(dot)com>, Shinya Kato <shinya11(dot)kato(at)gmail(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Nisha Moond <nisha(dot)moond412(at)gmail(dot)com>, Peter Eisentraut <peter(at)eisentraut(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Euler Taveira <euler(at)eulerto(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, "Jonathan S(dot) Katz" <jkatz(at)postgresql(dot)org>
Subject: Re: Logical Replication of sequences
Date: 2026-01-20 03:57:30
Message-ID: CAA4eK1JQERAwQhfG7vnaMoAKiuupXedhQPdHXjprbdZgyh0HJQ@mail.gmail.com
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On Tue, Jan 20, 2026 at 8:38 AM Hayato Kuroda (Fujitsu)
<kuroda(dot)hayato(at)fujitsu(dot)com> wrote:
>
> Dear Alexander,
>
> > FWIW, this issue is not reproduced at 7a485bd64~1, maybe this should be
> > taken into account.
>
> To confirm, are you saying that the issue cannot be reproduced before 7a485bd64
> right? I think it's because try_relation_open() is used in pg_get_sequence_data().
> Before the commit we forcibly open the relation and raise an ERROR if it fails.
> The sequencesync worker exits and tries again - everything is OK.
>
> After the commit, however, we allow to fail opening and the SQL function returns
> NULL - this can cause the assertion failure.
>

Right, this is the reason. Similar to the below check [1], introduced
in commit 7a485bd64, we need to check for null values in the
client-side and ERROR out accordingly.

[1]
+ if (entry->null_seqtuple)
+ pg_fatal("failed to get data for sequence
\"%s\"; user may lack "
+ "SELECT privilege on the
sequence or the sequence may "
+ "have been concurrently dropped",
+ tbinfo->dobj.name);

--
With Regards,
Amit Kapila.

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