Обсуждение: Check Replication lag

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Check Replication lag

От
Pawan Sharma
Дата:
Hello Team,

Is there a way to monitor the replication lag, where replica nodes are configured through aws s3.

Is not in a synced replica setup where master node will push the wal files to aws s3 and we are taking and replaying those wal files on a replica node.

-Pawan




Re: Check Replication lag

От
hubert depesz lubaczewski
Дата:
On Mon, Oct 11, 2021 at 05:58:03PM +0530, Pawan Sharma wrote:
> Is there a way to monitor the replication lag, where replica nodes are
> configured through aws s3.

You can check it on replica, by issuing:
select now() - pg_last_xact_replay_timestamp();

and it will show you, more or less, what is your current lag.

Best regards,

depesz




Re: Check Replication lag

От
Pawan Sharma
Дата:
Hello  Depesz, 

Thanks for your quick response, let me give some overview of our cluster setups.  Actually we have a Patroni cluster running with one replica (Replica 1) in the same data center with no data lag. whereas we have configured one more replica(Replica 2) in a different data center through AWS S3 WAL shipping and replaying. 

So we can easily check Patroni replica (Replica1) lag using the patronictl list command. but I am looking how I can check replication lag of Replica 2 which is configured through AWS.

As I have checked with above query I am getting same response from both the replicas. whereas on Replica2 there is some lag exist.


I have created dummy table on master node and its synced on replica1 simultaneously but it taking hours to sync on replica2.


Regards,
Pawan



  



On Mon, Oct 11, 2021 at 6:22 PM hubert depesz lubaczewski <depesz@depesz.com> wrote:
On Mon, Oct 11, 2021 at 05:58:03PM +0530, Pawan Sharma wrote:
> Is there a way to monitor the replication lag, where replica nodes are
> configured through aws s3.

You can check it on replica, by issuing:
select now() - pg_last_xact_replay_timestamp();

and it will show you, more or less, what is your current lag.

Best regards,

depesz