That I know, if standby is down, you cannot know exactly the last applied transaction log file.
But you could get agross 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.