Re: Replication delay

Thanks so much.

On 11 Aug 2013, at 9:50 PM, Michael Paquier wrote:

> 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
>
> Regards,
> --
> Michael