May 2018
Intermediate to advanced
576 pages
30h 25m
English
The connection limit is applied during the session connection. Raising this limit will never affect any connected users. Lowering the limit doesn't have any effect either, unless they try to disconnect and reconnect.
So, if you lower the limit, you should immediately check to see whether there are more sessions connected than the new limit you just set. Otherwise, there may be some surprises in case there is a crash:
postgres=> SELECT rolconnlimit FROM pg_roles WHERE rolname = 'fred'; rolconnlimit-------------- 1(1 row)postgres=> SELECT count(*) FROM pg_stat_activity WHERE usename = 'fred'; count------- 2(1 row)
If you have more connected sessions than the new limit, you can ask users politely to disconnect, or apply the next ...