| From: | Decibel! <decibel(at)decibel(dot)org> |
|---|---|
| To: | Nikolas Everett <nik9000(at)gmail(dot)com> |
| Cc: | "Gregory Stark" <stark(at)enterprisedb(dot)com>, "Josh Berkus" <josh(at)agliodbs(dot)com>, "Greg Smith" <gsmith(at)gregsmith(dot)com>, Postgres <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: How is random_page_cost=4 ok? |
| Date: | 2008-10-15 15:06:58 |
| Message-ID: | 754BF190-FE36-490C-83C6-A28C5CAEEF44@decibel.org |
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| Lists: | pgsql-hackers |
On Oct 10, 2008, at 7:41 PM, Nikolas Everett wrote:
> In any case your experience doesn't match mine. On a machine with a
> sizable
> raid controller setting random_page_cost higher does generate, as
> expected,
> plans with more bitmap heap scans which are in fact faster.
>
> We're running postgres backed by a NetApp 3020 via fiber and have
> had a lot of success setting random page cost very high (10).
> Sequential reads are just that much faster. I'm not sure if thats
> because we've configured something wrong or what, but thats a
> really useful knob for us.
Is your workload OLTP or OLAP? Promoting seqscans in an OLTP
environment seems to be a really bad idea to me...
--
Decibel!, aka Jim C. Nasby, Database Architect decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828
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