Обсуждение: FW: Performance 8.4.0

The database is 8gb currently. Use to be a lot bigger but we removed all large objects out and developed a file server
storagefor it, and using default page costs for 8.4, I did have it changed in 8.1.4 

-----Original Message-----
From: Robert Haas [mailto:robertmhaas@gmail.com]
Sent: Sunday, 2 August 2009 11:26 PM
To: Chris Dunn
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Performance 8.4.0

On Fri, Jul 31, 2009 at 12:22 AM, Chris Dunn<chris.dunn@bigredsky.com> wrote:
> constraint_exclusion = on

This is critical if you need it, but a waste of CPU time if you don't.
 Other than that your paramaters look good.  Are you using the default
page cost settings?  I see you have 12 GB RAM; how big is your
database?

...Robert

On Sun, Aug 2, 2009 at 10:04 PM, Chris Dunn<chris.dunn@bigredsky.com> wrote:
> The database is 8gb currently. Use to be a lot bigger but we removed all large objects out and developed a file
serverstorage for it, and using default page costs for 8.4, I did have it changed in 8.1.4 

You might want to play with lowering them.  The default page costs
make page accesses expensive relative to per-tuple operations, which
is appropriate if you are I/O-bound but not so much if you are CPU
bound, and especially if the whole database is memory resident.  I'd
try something like random_page_cost = seq_page_cost = 0.1 for
starters, or whatever values were working for you in 8.1, but the
sweet spot may be higher or lower.

...Robert