On Tue, 2020-11-24 at 19:54 +0530, Nikhil Shetty wrote: > We have one Primary and three Standby Postgresql setup. Two standby in DC and one standby in DR. > > We have configured streaming replication.When there are a lot of write transactions > in the master, we observed that DR lags behind the master for 5-6 hours. We initially > thought this could be because of the slow network between DC and DR and this is normal > but when we saw the replay_lsn and receive_lsn , they had a huge difference. > > DR standby was receiving the WAL's in time and there was no delay, the delay was in > replaying the lag. Can anybody point me to where I can start with the investigation? > DC (Master and 2 Standby) and DR(Standby) have the same setup in terms of storage > and some database configuration parameters but DR has a little less CPU and RAM. If there is a delay replaying WAL, the cause is probably a replication conflict. Set "hot_standby = off" on the standby to avoid the problem totally. If you want queries on the standby, set "max_standby_streaming_delay" to 0 to keep replication from falling behind. Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com
