Re: Correct query to check streaming replication lag - Mailing list pgsql-general

From Sameer Kumar
Subject Re: Correct query to check streaming replication lag
Date
Msg-id CADp-Sm5PzvwjwG=mc_i=DKKU_-V62LQP4rMvi+Dem05NvOQXgg@mail.gmail.com
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In response to Correct query to check streaming replication lag  (Granthana Biswas <granthana@zedo.com>)
Responses Re: Correct query to check streaming replication lag  (Granthana Biswas <granthana@zedo.com>)
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On Fri, Jan 17, 2014 at 5:31 PM, Granthana Biswas <granthana@zedo.com> wrote:


Thank you Sameer for your reply. Is there any other query that would help get exact replication lag?


You 2nd Query is the most accurate you can get. 
 
2. SELECT CASE WHEN pg_last_xlog_receive_location() = pg_last_xlog_replay_location() THEN 0 ELSE EXTRACT (EPOCH FROM now() - pg_last_xact_replay_timestamp()) END AS log_delay;
For reason same as above, this won't be exact but the most accurate you can get.
You can get lags in terms of bytes (and I have always believed that makes more sense).


May I ask, why are you looking for this info? Is it purely monitoring?

Regards
Sameer
Ashnik Pte Ltd.

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