On Tue, Apr 3, 2012 at 12:16 PM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote: > On Tue, Apr 3, 2012 at 12:01 PM, Jon Nelson <jnelson+pgsql@xxxxxxxxxxx> wrote: >> I have a situation that I'd like some help resolving. >> Using PostgreSQL 8.4.<reasonably recent> on Linux, I have three things >> coming together that cause me pain. I have a VIEW used by a bunch of >> queries. Usually, these queries are fairly short (subsecond) but >> sometimes they can be very long (days). I also update this view with >> CREATE OR REPLACE VIEW every 15-30 minutes. What I observe, sometimes, >> is this: >> >> 1. query A comes in. It's a big one. >> 2. another process comes along, needs to update the view definition. >> It issues create or replace view. It blocks on [1]. >> 3. queries B through N come in, are blocked by [2], which is blocked by [1]. >> 4. pandemonium! >> >> I can reduce (some) but not eliminate the need to update the view >> multiple times a day. What might be some good ways to prevent queries >> B through N blocking? >> >> Addendum: I can work around the issue by timing out and failing the >> CREATE OR REPLACE VIEW (by canceling the query) after a short >> duration, but is there a better way? > > Yeah -- this is just asking for trouble. Why do you have to replace > the view every 30 minutes? Your solution is probably going to involve > not doing that. As I said, I can reduce the frequency, but not eliminate it. I'm curious - if views are little more than sql macros, by the time the query has begun to execute why is a lock still needed on the view definition? -- Jon -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
