From: | Tatsuo Ishii <ishii(at)postgresql(dot)org> |
---|---|
To: | masao(dot)fujii(at)gmail(dot)com |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: failover vs. read only queries |
Date: | 2010-06-09 08:56:19 |
Message-ID: | 20100609.175619.98877714.t-ishii@sraoss.co.jp |
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Lists: | pgsql-hackers |
> When the trigger file is created while the recovery keeps
> waiting for the release of the lock by read only queries,
> it might take a very long time for the standby to become
> the master. The recovery cannot go ahead until those read
> only queries have gone away. This would increase the downtime
> at the failover, and degrade the high availability.
>
> To fix the problem, when the trigger file is found, I think
> that we should cancel all the running read only queries
> immediately (or forcibly use -1 as the max_standby_delay
> since that point) and make the recovery go ahead. If some
> people prefer queries over failover even when they create the
> trigger file, we can make the trigger behavior selectable in
> response to the content of the trigger file like pg_standby
> does.
>
> This problem looks like a bug, so I'd like to fix that for
> 9.0. But the amount of code change might not be small.
> Thought?
+1. Down time of HA system is really important for HA users.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp
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