On Mon, 2026-03-23 at 05:55 +0000, Subramanian,Ramachandran wrote:
> Thank you so much for your guidance, Today morning I noticed the columns being null .
>
> > streaming | 0/491179E8 | 0/491179E8 | 0/491179E8 | 0/491179E8 | | | |
>
> Does it make sense to use the below SQL as a primary health check ?
>
> [postgres@Source_server~]$ psql -p 5432 -c " select pg_wal_lsn_diff(sent_lsn,replay_lsn) from pg_stat_replication"
> pg_wal_lsn_diff
> -----------------
> 0
> (1 row)
No; you want to measure the lag between the primary's current WAL position and
what was already replayed on the standby:
SELECT pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn)
FROM pg_stat_replication;
Yours,
Laurenz Albe
