Re: query tuning - Mailing list pgsql-general

From scott.marlowe
Subject Re: query tuning
Date
Msg-id Pine.LNX.4.33.0308180953270.7025-100000@css120.ihs.com
Whole thread Raw
In response to query tuning  (Dave Cramer <dave@fastcrypt.com>)
List 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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