On Sun, 2012-03-18 at 21:06 -0700, Aleksey Tsalolikhin wrote: > Hi. When pg_dump runs, our application becomes inoperative (too > slow). I was going to ask if nice'ing the postgres backend process > that handles the COPY would help but I just realized probably the > pg_dump takes out locks when it runs and nice'ing it would just make > it run longer... > > However the man page says "pg_dump does not block other users > accessing the database (readers or writers)." But if we run a > pg_dump, the phone starts ringing, users are complaining that the web > app is not working. > > Would appreciate some pointer to help me reconcile these two > apparently contradictory facts. >
Depends on what your app is doing. It doesn't block any usual use of the database: DML are all accepted. But you cannot drop a table that pg_dump must save, you cannot change its definition. So there are some DDL commands you cannot use during a dump. Other than this, your users shouldn't be blocked. If it happens again, you should look at pg_locks and pg_stat_activity to understand what's going on. -- Guillaume http://blog.guillaume.lelarge.info http://www.dalibo.com -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
