aditya desai <admad123@xxxxxxxxx> writes: > We have a Postgres 11.16 DB which is continuously connected to informatica > and data gets read from it continuously. > When we have to ALTER TABLE.. ADD COLUMN.. it gets blocked by the SELECTs > on the table mentioned by process above. > Is there any way to ALTER the table concurrently without getting blocked? > Any parameter or option? Can someone give a specific command? ALTER TABLE requires exclusive lock to do that, so it will queue up behind any existing table locks --- but then new lock requests will queue up behind its request. So this'd only happen if your existing reading transactions don't terminate. Very long-running transactions are unfriendly to other transactions for lots of reasons including this one; see if you can fix your application to avoid that. Or manually cancel the blocking transaction(s) after the ALTER begins waiting. regards, tom lane
