Re: Measuring replication lag time

On Wed, Feb 22, 2012 at 5:40 PM, Stuart Bishop <stuart(at)stuartbishop(dot)net>wrote:

Hi.
>
> I need to measure how far in the past a hot standby is, async
> streaming replication.
>
> On the Hot Standby, "select
> age(current_timestamp,pg_last_xact_replay_timestamp())" gets me this
> (or close enough for my purposes - I understand that if there are no
> updates, there are no logs to replay and the lag time will increase).
>
> Is there some way to get this same information on the master?
> pg_stat_replication contains the log information, but I can't see how
> to map this to a timestamp.
>
> Is there a better way of measuring this?
>

Comparing "pg_controldata" output on prod and standby might help you with
this.

Thanks,
VB