2007/10/23, Martin Marques <[EMAIL PROTECTED]>: > Martin Marques escribió: > > Pavel Stehule wrote: > >> > >> try > >> > >> set work_mem to '8MB'; > >> and > >> explain analyze select .. > > > > These things didn't help. What changed the plan completely was this: > > > > seq_page_cost = 5.0 # measured on an arbitrary scale > > cpu_tuple_cost = 0.05 # same scale as above > > Can someone explain how this parameters are measured? What is 5.0 in > this case for seq_page_cost? >
http://www.postgresql.org/docs/8.2/interactive/runtime-config-query.html 5.0 means so seq scan will be expensive for optimaliser, and optimaliser will prefer index scan. ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
