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Re: Maximum Availability Architecture(MAA) for PostgreSQL - Mailing list pgsql-admin

From Wei Shan
Subject Re: Maximum Availability Architecture(MAA) for PostgreSQL
Date
Msg-id CAFe9ZTqVU7+JV8AM7uAGy3DKxHXQ3d-k2VofK==zB73c74axHA@mail.gmail.com
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In response to Re: Maximum Availability Architecture(MAA) for PostgreSQL  (Jan Lentfer <Jan.Lentfer@web.de>)
Responses Re: Maximum Availability Architecture(MAA) for PostgreSQL
Re: Maximum Availability Architecture(MAA) for PostgreSQL
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Hi Jay,

I totally agree with you that having a pair hot standbys will be good. What do you mean by "using WAL shipping in addition to WAL receivers"?According to the documentation, if I configure replication slot,  "the master does not remove WAL segments until they have been received by all standbys". In sync replication, if the standby is down, the transaction will not be able to commit. However, if we have a pair, as long as 1 of the hot standby is up, the transaction will still go through.

Hi Jan,

Technically, 2 instance of pg-pool will suffice. However, if we have to bring 1 instance down for maintenance, there's no standby if the master crashes.

Anyway, I do realise a tiny flaw in my design, pg-pool is not a active/active design. It means there's a wasted resource. At least my pair of hot standbys could serve read queries..



On 8 April 2015 at 20:44, Jan Lentfer <Jan.Lentfer@web.de> wrote:
Am 2015-04-08 10:22, schrieb Wei Shan:
In the PostgreSQL world, what do you guys think would be the
equivalent?

Attached is a diagram I have thought of. Clusters of pg-pool2 used to
load balance the connection in and for connection failover when a DB
crashes. Between master and slave, sync replication is being used for
zero-data-loss.

 Why do you need 3 pg-pool instances? 2 instances uses watchdog should be sufficient?
And if you plan to use sync replication you need to plan for 3 PostgreSQL Servers (a 3rd one that the sync replication can fail-over to).

Regards,


Jan


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Regards,
Ang Wei Shan

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