I said:
> Carlos Moreno <moreno@mochima.com> writes:
>> One quick question, Tom, before some general comments and
>> reply to the other messages... Where would I specify any
>> locks the software wants to do?
> If you are not issuing any explicit "LOCK" SQL commands, then you can
> disregard my theory.
Actually, that's too simple. Are you creating and dropping tables,
or issuing schema-change commands (such as ADD COLUMN or RENAME)?
All of those things take exclusive locks on the tables they modify.
Ordinary SELECT/INSERT/UPDATE/DELETE operations can run in parallel with
pg_dump, but messing with the database structure is another story.
I guess the real question here is whether your app is actually stopped
dead (as it would be if waiting for a lock), or just slowed to a crawl
(as a performance problem could do). I cannot tell if your "frozen"
description is hyperbole or literal truth.
One thing that might help diagnose it is to look at the output of ps
auxww (or ps -ef on SysV-ish platforms) to see what all the backends are
currently doing while the problem exists.
regards, tom lane