Unnecessary WAL archiving after failover

From: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Unnecessary WAL archiving after failover
Date: 2012-02-29 10:48:36
Message-ID: CAHGQGwGQQLrODSVRb=HBTt6bj-dvz0NS=_jcNZRO9EMbUaLx0g@mail.gmail.com
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Hi,

In streaming replication, after failover, new master might have lots
of un-applied
WAL files with old timeline ID. They are the WAL files which were recycled as a
future ones when the server was running as a standby. Since they will never be
used later, they don't need to be archived after failover. But since they have
neither .ready nor .done file in archive_status, checkpoints after
failover newly
create .reacy files for them, and then finally they are archived.
Which might cause
disk I/O spike both in WAL and archive storage.

To avoid the above problem, I think that un-applied WAL files with old
timeline ID
should be marked as already-archived and recycled immediately at the end of
recovery. Thought?

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

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