On Wed, 2010-08-04 at 09:14 -0400, Robert Haas wrote: > On Tue, Aug 3, 2010 at 3:03 AM, Hannu Krosing <ha...@2ndquadrant.com> wrote: > > In case of fully cached database it is closer to 1. > > In the case of a fully cached database I believe the correct answer > begins with a decimal point.
The number 1 here was suggested in relation to seq_page_cost, which is 1. For fully cached db there is no additional seek time for random access, so seq_page_cost == random_page_cost. Of course there are more variables than just *_page_cost, so if you nail down any other one, you may end with less than 1 for both page costs. I have always used seq_page_cost = 1 in my thinking and adjusted others relative to it. -- Hannu Krosing http://www.2ndQuadrant.com PostgreSQL Scalability and Availability Services, Consulting and Training -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
