On Tue, 2009-05-19 at 00:33 +0200, Dimitri wrote: > > > > In particular, running the tests repeatedly using > > H.REF_OBJECT = '0000000001' > > rather than varying the value seems likely to benefit MySQL. The > > let me repeat again - the reference is *random*, > the '0000000001' value I've used just to show a query execution > plan. > > also, what is important - the random ID is chosen in way that no one > user use the same to avoid deadlocks previously seen with PostgreSQL > (see the "Deadlock mystery" note 2 years ago > http://dimitrik.free.fr/db_STRESS_BMK_Part1.html#note_4355 ) OK, didn't pick up on that. (Like Tom, I was thinking query cache) Can you comment on the distribution of values for that column? If you are picking randomly, this implies distribution is uniform and so I am surprised we are mis-estimating the selectivity. > I think yes (but of course I did not try to replay it several times) If you could that would be appreciated. We don't want to go chasing after something that is not repeatable. -- 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
