Re: Correct query to check streaming replication lag

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

Regards,
Granthana

Regards,
Granthana

On Fri, Jan 17, 2014 at 2:46 PM, Sameer Kumar <sameer(dot)kumar(at)ashnik(dot)com>wrote:

>
> On Tue, Jan 14, 2014 at 2:31 PM, Granthana Biswas <granthana(at)zedo(dot)com>wrote:
>
>> Can anyone please tell me which of the following is the correct
>> replication lag query to find streaming replication lag in seconds?
>>
>> IMHO none is 'correct'. :-)
>
> 1. SELECT extract(seconds from (now() - pg_last_xact_replay_timestamp()))
>> AS time_lag;
>>
>> This is the difference between now and last replayed log. What if the
> last transaction on master has happened a few minutes ago?
>
>
>> 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.
>
> Best Regards,
> *Sameer Kumar | Database Consultant*
>
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