Horton

Re: logical replication: restart_lsn can go backwards (and more), seems broken since 9.4

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Tomas Vondra <tomas@vondra.me>
Cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2024-11-13T09:38:27Z
Lists: pgsql-hackers 
On Tue, Nov 12, 2024 at 6:29 PM Tomas Vondra <tomas@vondra.me> wrote:
>
> Sure, maybe fixing LogicalIncreaseRestartDecodingForSlot() is enough to
> fix this particular case. But I'd be happier if we could also add
> asserts checking the LSN advances, to detect similar issues that we may
> be unaware of yet.
>

As most of us lean towards fixing
LogicalIncreaseRestartDecodingForSlot(), let's fix that in the HEAD
and back branches. Separately we can consider other asserts just for
HEAD that you think will make the code robust and help avoid such bugs
in the future.

-- 
With Regards,
Amit Kapila.

Commits

  1. Fix a possibility of logical replication slot's restart_lsn going backwards.

  2. Introduce logical decoding.