that helped me to get rid of the issues, using pg_locks and pg_stat_activity I was able to find out concurrent session which was not allowing to hold exclusive lock.
> Laurenz Albe <laurenz.albe@cybertec.at> writes: > >> On Tue, 2020-01-07 at 14:58 +0530, Shrikant Bhende wrote: >>> I am trying to add a column to a table but it's not working, I have also tried >>> reindex and drop on the same table but those commands are also getting stuck. > >> There is a concurrent session which has an open transaction which >> holds some lock on the table in question. > > Yes, that looks like the cause. The pg_locks view could help you > find the culprit session.
Yeah, and IMO the pg_blocking_pids($blocked-guys-pid) function is pretty snazzy too :-)