Claudio Freire <klaussfreire@xxxxxxxxx> writes: > On Wed, Apr 13, 2011 at 4:32 PM, Kevin Grittner > <Kevin.Grittner@xxxxxxxxxxxx> wrote: >> If you model the costing to reflect the reality on your server, good >> plans will be chosen. > Wouldn't it be "better" to derive those costs from actual performance > data measured at runtime? > Say, pg could measure random/seq page cost, *per tablespace* even. > Has that been tried? Getting numbers that mean much of anything is a slow, expensive process. You really don't want the database trying to do that for you. Once you've got them, you *really* don't want the database editorializing on them. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
