Horton

Re: The XLogFindNextRecord() routine find incorrect record start point after a long continuation record

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: Andrey Lepikhov <a.lepikhov@postgrespro.ru>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Date: 2019-11-07T03:41:36Z
Lists: pgsql-bugs 
On Thu, Nov 07, 2019 at 02:41:29AM +0900, Fujii Masao wrote:
> I created the problematic WAL file artificially by using
> pg_logical_emit_message() and sucessfully reproduced
> the error.

Good idea.  I didn't know this one.

> I attached the WAL file that I created. You can
> reproduce the issue by
> 
>     pg_waldump 000000010000000000000008 -s 0/08002028

Assertion failure reproduced here.

> The patch looks good to me. Barrying any objection, I will commit it.
> XLogFindNextRecord() must return the valid record starting position,
> but currently could return the starting position of WAL page
> (not valid WAL record) in the case that you described. This is
> the cause of the issue.

No issues from here, thanks for taking care of it.
--
Michael

Commits

  1. Fix assertion failure when running pgbench -s.

  2. Fix pg_xlogdump so that it handles cross-page XLP_FIRST_IS_CONTRECORD record.