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

Andrei Lepikhov <a.lepikhov@postgrespro.ru>

From: Andrey Lepikhov <a.lepikhov@postgrespro.ru>

To: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>

Date: 2019-11-06T02:40:48Z

Lists: pgsql-bugs

Attachments

0001-Correct-the-algorithm-of-definition-of-WAL-record-st.patch (text/x-patch)

I found this in our multimaster project on PostgreSQL 11.5. It is 
difficult to reproduce this error, but I will try to do it if necessary.

The rest of a continuation WAL-record can exactly match the block size. 
In this case, we need to switch targetPagePtr to the next block before 
calculating the starting point of the next WAL-record.
See the patch in attachment for the bug fix.

-- 
Andrey Lepikhov
Postgres Professional
https://postgrespro.com
The Russian Postgres Company

Commits

Fix assertion failure when running pgbench -s.
- 1accf9974821 9.4.25 landed
- b1bebc2cee58 9.5.20 landed
- aa7cd6a8e741 9.6.16 landed
- 127ad57f5d44 10.11 landed
- fb53c4c07fec 11.6 landed
- e5cfb8cbbe91 12.1 landed
- a0c96856e8b3 13.0 landed
Fix pg_xlogdump so that it handles cross-page XLP_FIRST_IS_CONTRECORD record.
- bab7823a49bb 10.0 cited