Re: Hash join on int takes 8..114 seconds - Mailing list pgsql-performance

PFC <lists@peufeu.com> writes:
> Index on orders_products( product_id ) and orders_products( order_id ):
>     => Same plan

>     Note that in this case, a smarter planner would use the new index to
> perform a BitmapAnd before hitting the heap to get the rows.

Considering that the query has no constraint on
orders_products.order_id, I'm not sure what you think the extra index is
supposed to be used *for*.

(Well, we could put orders as the outside of a nestloop and then we'd
have such a constraint, but with 30000 orders rows to process that plan
would lose big.)

(And yes, the planner did consider such a plan along the way.
See choose_bitmap_and.)

            regards, tom lane