Re: SQL command in Slave Database - Monitor Replication

Hi Matheus,

Thanks for your answer.  I do not have access to the primary database. So, I cannot run a SQL in there.

I need to run the command in the Slave database that tells me whether the replication is still working or not.

Regards,

Alberto.

Alberto Olivares Colas
Technical Consultant

Snowflake Software

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On 4 July 2015 at 15:37, Matheus de Oliveira <matioli.matheus@gmail.com> wrote:

On Fri, Jul 3, 2015 at 12:03 PM, Alberto Olivares <alberto.olivares@snowflakesoftware.com> wrote:

Is there any SQL command that I can run on the slave database to check if the replication is still working or not? I know that you can check the postgresql.conf but I want to do it directly on the SQL panel.

Database:  Postgresql 9.1 on Linux

You can query pg_stat_replication (since 9.1+) on the primary server, it will return one row for each secondary connected.

If you were on 9.2+ you could even use pg_xlog_location_diff to get the lag in bytes of data sent to the standby:

    SELECT
        application_name,
        client_addr,
        pg_size_pretty(pg_xlog_location_diff(pg_current_xlog_location(), sent_location)) AS sent_lag

    FROM pg_stat_replication;

You can use write_location and replay_location similarly.

On 9.1 you'll have to do this math by yourself if you want or create your own pg_xlog_location_diff.

OBS: pg_stat_replication will only show standby connected through streaming replication, log shipping cannot be verified this way.

Best regards,

--

Matheus de Oliveira