2007/10/23, Martin Marques <martin@xxxxxxxxxxxxxxx>:> 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, andoptimaliser will prefer index scan. ---------------------------(end of broadcast)---------------------------TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
