<me@alternize.com> writes:
> the pg_dump of our 2.45gb db takes an awfully long 45min during which db
> services come more or less to a hold.
> this does not seem right to me.
Me either. Do you have operations that are taking exclusive locks on
tables? pg_dump takes AccessShareLock (ie, a reader's lock) on every
table in sight, to make sure the tables don't disappear or change schema
underneath it. This doesn't cause any problem for concurrent SELECT,
INSERT/UPDATE/DELETE, nor plain VACUUM ... but it could result in
blocking schema changes, VACUUM FULL, etc. And if so, those would
in turn block everything else.
Looking at pg_locks would confirm or deny this idea.
regards, tom lane