check postgres replication status

Question

Can someone suggest the steps to check pgsql replication status and when to say replication is not happening properly?

We use streaming replication with pgsql9.0 and pgsql9.4

Thanks.

Answer 1

I use following SQL queries to check status on Postgres v11 usually.

On master:

select * from pg_stat_replication; 

On replica (streaming replication in my case):

select * from pg_stat_wal_receiver; 

Answer 2

On your master, pg_stat_replication provides data about ongoing replication:

select client_addr, state, sent_location, write_location,         flush_location, replay_location from pg_stat_replication; 

On postgresql v10:

select client_addr, state, sent_lsn, write_lsn,     flush_lsn, replay_lsn from pg_stat_replication;