On Tue, Jun 16, 2009 at 03:37:42PM +0200, Alberto Dalmaso wrote: > Hi everybody, I'm creating my database on postgres and after some days > of hard work I'm arrived to obtain good performance and owfull > performace with the same configuration. > I have complex query that perform very well with mergejoin on and > nestloop off. > If I activate nestloop postgres try to use it and the query execution > become inconclusive: after 3 hours still no answare so I kill the query. > Tht's ok but, with this configuration, very simple and little query like > "slect colum from table where primarykey=value bacome incredibly slow. > The only solutionI found at the momento is to set mergejoin to off > before doing this query. > That is an awfull solution because with that solution I have to change > all the software (a big, old software) in the (many) points in witch > this kind of query are used (the same problem to set to off mergejoin > for all the system and activate it on che connection that have to make > the hard query). > Do you have any suggestion to accelerate both complex and silply query? > I've tried a lot of configuration in enabling different "Planner Method > Configuration" but the only combination that really accelerate hard > query is mergejoin on and nestloop off, other settings seems to be > useless. > Thank's in advance. It would be helpful if you posted EXPLAIN ANALYZE results for both queries. This will require you to run each query to completion; if that's not possible for the 3 hour query, at least run EXPLAIN and post those results. - Josh / eggyknap
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