Horton

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

Tomas Vondra <tomas@vondra.me>

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From: Tomas Vondra <tomas@vondra.me>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2024-11-13T11:53:34Z
Lists: pgsql-hackers 

On 11/13/24 10:38, Amit Kapila wrote:
> 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.
> 

+1 to that


regards

-- 
Tomas Vondra

Commits

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

  2. Introduce logical decoding.