pg.ddx.io pgsql-performance@postgresql.org mailing list archivehelp / color / mirror / Atom feed
how explain works 2+ messages / 2 participants [nested] [flat]
* how explain works @ 2011-04-11 23:02 Radhya sahal <rad_cs_2006@yahoo.com> 0 siblings, 1 reply; 2+ messages in thread From: Radhya sahal @ 2011-04-11 23:02 UTC (permalink / raw) To: pgsql-performance Dear ,all plz could any one help me !!! how explian works as math equations to estimate cost with constatn query parameters such as cpu_tuple cost ,random page cost ...etc i want maths expression in order to know how these parameters will effect in cost ??? please any one can help me ?? Regards Radhya... ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: how explain works @ 2011-04-11 23:09 Nathan Boley <npboley@gmail.com> parent: Radhya sahal <rad_cs_2006@yahoo.com> 0 siblings, 0 replies; 2+ messages in thread From: Nathan Boley @ 2011-04-11 23:09 UTC (permalink / raw) To: Radhya sahal <rad_cs_2006@yahoo.com>; +Cc: pgsql-performance > how explian works as math equations to estimate cost with constatn query > parameters > such as cpu_tuple cost ,random page cost ...etc > i want maths expression in order to know how these parameters will effect > in cost ??? The expressions are complicated, and they are certainly not linear as you seem to think from your previous post. > please any one can help me ?? What do you need this for? If your goal is to optimize a real application, then you should just vary the cost parameters and measure the resulting change in query times. If your interests are academic, there were some excellent suggestions for places to start in response to your previous post. Best, Nathan ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2011-04-11 23:09 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2011-04-11 23:02 how explain works Radhya sahal <rad_cs_2006@yahoo.com> 2011-04-11 23:09 ` Nathan Boley <npboley@gmail.com>
This inbox is served by DDX for PostgreSQL; see mirroring instructions for how to clone and mirror all data and code used for this inbox