Re: Optimize date query for large child tables: GiST or GIN?

David Jarvis <thangalin(at)gmail(dot)com> writes:
> I was hoping to eliminate this part of the query:
> (cast(extract( YEAR FROM m.taken ) + greatest( -1 *
> sign(
> (extract( YEAR FROM m.taken )||'-12-31')::date -
> (extract( YEAR FROM m.taken )||'-01-01')::date ), 0
> ) AS text)||'-12-31')::date

> That uses functions to create the dates, which is definitely the problem.

Well, it's not the functions per se that's the problem, it's the lack of
a useful index on the expression. But as somebody remarked upthread,
that expression doesn't look correct at all. Doesn't the whole
greatest() subexpression reduce to a constant?

regards, tom lane