Bill, > The only one that seems practical (to me) is random_page_cost. The > others are all configuration options that I (as a DBA) want to be able > to decide for myself. Actually, random_page_cost *should* be a constant "4.0" or "3.5", which represents the approximate ratio of seek/scan speed which has been relatively constant across 6 years of HDD technology. The only reason we make it a configuration variable is that there's defects in our cost model which cause users to want to tinker with it. Mind you, that's gotten better in recent versions as well. Lately I mostly tinker with effective_cache_size and the various cpu_* stats rather than modifying random_page_cost. -- --Josh Josh Berkus PostgreSQL @ Sun San Francisco
