Thread: How to check stream replication latest history status

How to check stream replication latest history status

From
徐志宇徐
Date:
    Hi All
   
      I set up Postgres 11 stream replication env.Use keepalived to control VIP and a script to check Postgres status.
      Usually. I could check the stream replication status by this view "pg_stat_replcation" on primary server.
      Check this view "pg_stat_wal_receiver" on standby server.
     
      Sometime the primary server abnormal or the network interrupt by unexpected issue.
     
      Both of them no record "pg_stat_replcation", "pg_stat_wal_receiver" on that time.
     
      I want to know the stream replication gap between primary and standby before standby promote.
      If the primary and standby have long replay_lag. I don't want to standby server promote.
     
      Is there any view or function which store the latest stream replication gap(replay_lag) between primary and standby ?
      Or it there any workaround to know this stream replication gap(replay_lag) infomation ?  Thanks for your help.

                                                                                  Jack.Xu

Re: How to check stream replication latest history status

From
Kyotaro Horiguchi
Date:
At Mon, 14 Nov 2022 00:09:36 +0800, 徐志宇徐 <xuzhiyuster@gmail.com> wrote in 
>       If the primary and standby have long replay_lag. I don't want to
> standby server promote.
> 
>       Is there any view or function which store the latest stream
> replication gap(replay_lag) between primary and standby ?
>       Or it there any workaround to know this stream replication
> gap(replay_lag) infomation ?  Thanks for your help.

replay_lag vanishes when the steram is gone. But commit timestamps
might work for you. You can see when the last replayed transaction on
the standby was commited on the primary.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center