| From: | "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com> |
|---|---|
| To: | Dave Cramer <dave(at)fastcrypt(dot)com> |
| Cc: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: query tuning |
| Date: | 2003-08-18 15:54:55 |
| Message-ID: | Pine.LNX.4.33.0308180953270.7025-100000@css120.ihs.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
On 14 Aug 2003, Dave Cramer wrote:
> I have a query which definitely runs faster when sequential scans are
> turned off. Which parameters do I tune? and which way?
>
> After quickly perusing the docs, and google, I think it is the
> random_page_cost?
Set your effective_cache_size correctly first, then lower random page cost
until you hit the sweet spot.
As someone else pointed out, you can also lower the cpu_***_cost
parameters, and often this is preferable. On boxes with fast memory /
CPUs, it's often good to get the planner in the state of mind of using the
CPU a little more, so it will pick a faster join method than it otherwise
would.
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