| From: | Manfred Koizar <mkoi-pg(at)aon(dot)at> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "Greg Sabino Mullane" <greg(at)turnstep(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: cpu_tuple_cost |
| Date: | 2005-03-17 08:20:55 |
| Message-ID: | rvei31lue913dme9uhrv38n24sslb2dh3i@email.aon.at |
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| Lists: | pgsql-performance |
On Mon, 14 Mar 2005 21:23:29 -0500, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I think that the "reduce random_page_cost" mantra
>is not an indication that that parameter is wrong, but that the
>cost models it feeds into need more work.
One of these areas is the cost interpolation depending on correlation.
This has been discussed on -hackes in October 2002 and August 2003
("Correlation in cost_index()"). My Postgres installations contain the
patch presented during that discussion (and another index correlation
patch), and I use *higher* values for random_page_cost (up to 10).
Servus
Manfred
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