On 10/23/2013 11:07 AM, David Kerr wrote:
On Tue, Oct 22, 2013 at 12:41:58PM -0500, andy wrote: - Hi all. - - My website is about to get a little more popular. I'm trying to add in - some measurements to determine an upper limit of how many concurrent - database connections I'm currently using. - - I've started running this: - - SELECT sum(numbackends) AS count, sum(xact_commit) as ttlcommit FROM - pg_stat_database; - - Every 10 seconds or so. I don't think its what I want though. It seems - way too small. I'm guessing that its not a measure of the previous 10 - seconds. Its a count of how many backends are in use at the exact - moment I run the sql. - - Is there a cumulative count someplace? - - Thanks for your time, - - -Andy You've gotten good info from the other guys on how to scale your're DB but to answer you're original question. I usually use this query: select count(*) from pg_stat_activity where state <> 'idle'; That gives you the # of "active" connections to your database and is something you want to try to get good metrics on. Idle connections have some overhead but if Active > # of CPUs your performance starts to degrade. Now, really that's pretty normal but, ideally, you need to know what the ratio of Active Connections to # CPUs still gives you acceptable performance. And that's really based on your app and hardware.
How often do you run that? Once a second? And graph it? I was doing it every 10 seconds, but it doesn't give me a good view of the system.
-Andy -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
