On Mon, 2009-05-18 at 20:00 +0200, Dimitri wrote: > >From my point of view it needs first to understand where the time is > wasted on a single query (even when the statement is prepared it runs > still slower comparing to MySQL). There is still a significant number of things to say about these numbers and much tuning still to do, so I'm still confident of improving those numbers if we needed to. In particular, running the tests repeatedly using H.REF_OBJECT = '0000000001' rather than varying the value seems likely to benefit MySQL. The distribution of values is clearly non-linear; while Postgres picks a strange plan for that particular value, I would guess there are also values for which the MySQL plan is sub-optimal. Depending upon the distribution of selected data we might see the results go either way. What I find worrying is your result of a scalability wall for hash joins. Is that a repeatable issue? -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
