Horton

Re: cpu_tuple_cost

Manfred Koizar <mkoi-pg@aon.at>

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From: Manfred Koizar <mkoi-pg@aon.at>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "Greg Sabino Mullane" <greg@turnstep.com>, pgsql-performance@postgresql.org
Date: 2005-03-17T08:20:55Z
Lists: pgsql-performance 
On Mon, 14 Mar 2005 21:23:29 -0500, Tom Lane <tgl@sss.pgh.pa.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