Re: Opptimizing projections containing unused columns

"Andrus" <kobruleht2@hot.ee> writes:
> Is it OK to put all filters to outer query WHERE clase?
> Or should I move as many filter conditions as possible to inner query so
> that inner query returns 10000 records instead of 500000 records.

> Is there difference in perfomance if inner query returs large number of rows
> which are filtered only by outer query ?

This question is too vague to be answerable --- especially if you want
an answer that applies across all 8.x releases.  I'd suggest
experimenting a bit using EXPLAIN ANALYZE to see what happens in your
actual application.

            regards, tom lane