Re: performance regression with 9.2

Dave Cramer <pg@fastcrypt.com> writes:
> This query is a couple orders of magnitude slower the first result is
> 9.2.1, the second 9.1

Thanks for sending me the test case off-list.  I found the reason why
I'd not been able to reproduce the problem: the index you're hoping it
will use is declared

"note_sets_parent_id_idx" btree (parent_id) WHERE parent_id IS NOT NULL

Apparently 9.2 is less bright than 9.1 about when it can use a partial
index.  I'm not sure where I broke that, but will look.

            regards, tom lane