Re: Replication lag from transaction logs

Thanks Keith I am looking something like the solution you suggested.

Once I run pg_controldata on the slave data directory it will be give me
the latest checkpoint like below. Can you let me know a bit more detail on
how can I get the approximate lag in the slave in bytes from this?

Latest checkpoint location: 2F9/B38DE758

On Mon 18 Jun, 2018, 6:53 PM Keith, <keith(at)keithf4(dot)com> wrote:

> You can use pg_controldata on any data directory to get its rough position
> in WAL replay, even when the database isn't running
>
> https://www.postgresql.org/docs/current/static/app-pgcontroldata.html
>
> On Mon, Jun 18, 2018 at 8:56 AM, Fabio Pardi <f(dot)pardi(at)portavita(dot)eu> wrote:
>
>> That I know, if standby is down, you cannot know exactly the last
>> applied transaction log file.
>>
>> But you could get a gross estimate if you check how many WAL files is
>> the standby behind, just listing the WAL files on the master and on the
>> standby.
>>
>> Given that you can login on the standby machine.
>>
>> regards,
>>
>> fabio pardi
>>
>>
>> On 18/06/18 14:43, Debraj Manna wrote:
>>
>> Is it possible to figure out the replication lag from transaction log
>> files in the slave and master without querying postgres on the slave?
>> Basically figuring out the replication lag in a slave when the postgres is
>> down in that slave.
>>
>>
>>
>