Horton

Re: Possible bug in logical replication.

Arseny Sher <a.sher@postgrespro.ru>

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From: Arseny Sher <a.sher@postgrespro.ru>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Michael Paquier <michael@paquier.xyz>, Simon Riggs <simon@2ndquadrant.com>, Arseny Sher <a.sher@postgrespro.ru>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, Sawada Masahiko <sawada.mshk@gmail.com>, konstantin knizhnik <k.knizhnik@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-06-15T15:27:56Z
Lists: pgsql-hackers

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Alvaro Herrera <alvherre@2ndquadrant.com> writes:

> Can somebody (Arseny, Konstantin, horiguti, Sawada) please confirm that
> Michaël's commit fixes the reported bug?

I confirm that starting reading WAL since restart_lsn as implemented in
f731cfa fixes this issue, as well as the second issue tushar mentioned
at [1]. I think that the code still can be improved a bit though --
consider the attached patch:
* pg_logical_replication_slot_advance comment was not very informative
  and even a bit misleading: it said that we use confirmed_flush_lsn and
  restart_lsn, but didn't explain why.
* Excessive check in its main loop.
* Copy-paste comment fix.

[1] https://www.postgresql.org/message-id/5f85bf41-098e-c4e1-7332-9171fef57a0a%40enterprisedb.com

--
Arseny Sher
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Commits

  1. Rewrite comments in replication slot advance implementation

  2. Fix a couple of bugs with replication slot advancing feature

  3. Ability to advance replication slots