"Anne Rosset" <arosset@xxxxxxxxxx> wrote: > -> Index Scan using role_oper_obj_oper > on role_operation (cost=0.00..93.20 rows=45 width=9) (actual > time=0.236..71.291 rows=6108 loops=1) > Index Cond: > (((object_type_id)::text = 'SfMain.Project'::text) AND > ((operation_category)::text = 'admin'::text) AND > ((operation_name)::text = 'admin'::text)) This looks like another case where there is a correlation among multiple values used for selection. The optimizer assumes, for example, that category = 'admin' will be true no more often for rows with operation_name = 'admin' than for other values of operation_name. There has been much talk lately about how to make it smarter about that, but right now there's no general solution, and workarounds can be tricky. In more recent versions you could probably work around this with a Common Table Expression (CTE) (using a WITH clause). In 8.3 the best idea which comes immediately to mind is to select from the role_operation table into a temporary table using whichever of those three criteria is most selective, and then join that temporary table into the rest of the query. Maybe someone else can think of something better. -Kevin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
