On 7 Jun 2004 at 16:00, Rod Taylor wrote:
> On Mon, 2004-06-07 at 15:45, Dan Langille wrote:
> > A production system has had a query recently degrade in performance.
> > What once took < 1s now takes over 1s. I have tracked down the
> > problem to a working example.
> What changes have you made to postgresql.conf?
Nothing recently (ie. past few months). Nothing at all really.
Perhaps I need to start tuning that.
> Could you send explain analyse again with SEQ_SCAN enabled but with
> nested loops disabled?
> Off the cuff? I might hazard a guess that effective_cache is too low or
> random_page_cost is a touch too high. Probably the former.
I grep'd postgresql.conf:
#effective_cache_size = 1000 # typically 8KB each
#random_page_cost = 4 # units are one sequential page fetch cost
NOTE: both above are commented out.
Dan Langille : http://www.langille.org/
BSDCan - http://www.bsdcan.org/