Fwd: Monitoring Replication on Master/Slave Postgres(9.1) - Mailing list pgsql-admin

From Shams Khan
Subject Fwd: Monitoring Replication on Master/Slave Postgres(9.1)
Date
Msg-id CAM42bopixMf9WLDZVo5U-T0eNyamKmObtcKG+ziFZT1kzLDJQQ@mail.gmail.com
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In response to Monitoring Replication on Master/Slave Postgres(9.1)  (Shams Khan <shams.khan22@gmail.com>)
List pgsql-admin
Thanks for the response Stuart...It was really helpful:

Below are some doubts I wanted to clarify..please read and suggest.
Can we also check if replication was broken earlier...somehow due to power failure of some other reasons in past...The reason I am asking is I am getting some discrepancies in data between master and slave...? I want to know the reason of it...

thanx

---------- Forwarded message ----------
From: Stuart Bishop <stuart@stuartbishop.net>
Date: Tue, Nov 27, 2012 at 2:03 PM
Subject: Re: [ADMIN] Monitoring Replication on Master/Slave Postgres(9.1)
To: Shams Khan <shams.khan22@gmail.com>


On Mon, Nov 26, 2012 at 5:05 PM, Shams Khan <shams.khan22@gmail.com> wrote:
> HI All,
>
> I want to know the ways to monitor the replication, whether the master and
> slave server are sync.

On the slave, run "SELECT now() - pg_last_xact_replay_timestamp() AS
time_lag;". That tells you how far behind in time the slave is.

> My question is how do we read these numbers(17A/342A6F78 and 17A/34366C30) I
> never got the same results on both servers. Is that mean slave is not synced
> with master?

With asynchronous replication, the slave will always lag behind the
master. The query I posted above will tell you by how much.

--
Stuart Bishop <stuart@stuartbishop.net>
http://www.stuartbishop.net/

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