From: Andrey Lepikhov <a.lepikhov@postgrespro.ru>
Subject: The XLogFindNextRecord() routine find incorrect record start point
 after a long continuation record
Organization: Postgres Professional
To: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Message-ID: <99303554-5dd5-06e6-f943-b3005ccd6edd@postgrespro.ru>
Date: Wed, 6 Nov 2019 07:40:48 +0500
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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

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