Re: Replication delay

From: Tatsuo Ishii <ishii(at)postgresql(dot)org>
To: michael(dot)paquier(at)gmail(dot)com
Cc: ascot(dot)moss(at)gmail(dot)com, pgsql-general(at)postgresql(dot)org
Subject: Re: Replication delay
Date: 2013-08-11 21:01:13
Message-ID: 20130812.060113.1771524864291728974.t-ishii@sraoss.co.jp
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> On Sun, Aug 11, 2013 at 5:51 AM, ascot(dot)moss(at)gmail(dot)com
> <ascot(dot)moss(at)gmail(dot)com> wrote:
>> Hi,
>>
>> I have a pair of PG servers, a master and a replica, all read-write queries are handled by the master, read-only ones are by the replica.
>>
>> From time to time the replica itself is too busy, all read-only queries will get inconsistent results because of replication lag, sometimes it can be longer than 6 minutes. I am thinking to add multiple replicas to off-load read-only queries, can you please suggest a way to monitor and failover the read-only query when the replication lag in a replica is more than 5 minutes?
> I assume that you could use pgpool for that. It has some monitoring
> features for replication delay and it can do read-only load balancing
> among several servers. You also shouldn't need to change your
> application.
> Have a look at its documentation to make an opinion:
> http://pgpool.projects.pgfoundry.org/pgpool-II/doc/pgpool-en.html

The url above is obsoleted. Please visit:

http://www.pgpool.net/docs/latest/pgpool-en.html
--
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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