On Sun, Jun 8, 2008 at 7:55 AM, Jaime Casanova <systemguards@xxxxxxxxx> wrote: > On Sun, Jun 8, 2008 at 1:34 AM, Scott Marlowe <scott.marlowe@xxxxxxxxx> wrote: >> On Sat, Jun 7, 2008 at 5:16 PM, Viktor Rosenfeld >> <rosenfel@xxxxxxxxxxxxxxxxxxxxxxx> wrote: >>>> >>>> Try this: >>>> >>>> begin; >>>> drop indexname; >>>> explain analyze select ...; >>>> rollback; >>> >>> That works, but I'm still looking for another way to deactivate the index. >>> The reason being, that my query load is randomly generated by a Java >>> program and I don't want to go and change the SQL compiler. >> >> Sorry, I'm out of ideas. I mean, you can turn off all indexes with >> set enable_indexscan=off but there's no other way to do it cheaply and >> in such a fine grained way. >> > > with "enable_indexscan=off" you're not turning indexes off but putting > a high cost in using them... the effect, most of the time, is that > indexes will not be used but you can't be sure... > > the better solution was the first one: dropping the index inside a > transaction, execute the explain analyze of the query and rollback the > transaction True. Also there's been some talk lately about how to add query planner controls to postgresql to control the planner. This being an open source project, I think it's pretty reasonable to put the onus of that kind of thing on the user community to take a first whack at before someone spends a lot of time instrumenting it in full in the core.
