I don't think random_page_cost actually corresponds with any real number anymore. I just treat it as an uncalibrated knob you can turn and benchmark the results at.
And, frankly, not a useful knob. You get much more useful results out of effective_cache_size and cpu_* costs than you get out of messing with random_page_cost, unless you're running on SSD or something which would justify a lower RPC, or if you're compensating for our poor n-distinct estimation for very large tables.
--Josh -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
