Re: HAVING push-down

On Fri, 2007-01-26 at 15:22 +0000, Gregory Stark wrote:
> "Simon Riggs" <simon@2ndquadrant.com> writes:
> 
> > I've just read a paper that says PostgreSQL doesn't do this. My reading
> > of the code is that we *do*  evaluate the HAVING clause prior to
> > calculating the aggregates for it. I thought I'd check to resolve the
> > confusion.
> >

> You mean in cases like this?
> 
> postgres=# explain select  count(*) from customer group by c_w_id,c_d_id,c_id having c_w_id = 1 and c_d_id=1 and
c_id=1;
>                                      QUERY PLAN                                     
> ------------------------------------------------------------------------------------
>  GroupAggregate  (cost=0.00..13.61 rows=1 width=12)
>    ->  Index Scan using pk_customer on customer  (cost=0.00..13.56 rows=4 width=12)
>          Index Cond: ((c_w_id = 1) AND (c_d_id = 1) AND (c_id = 1))
> (3 rows)

OK, thanks. I'll feedback to the author of the paper I was reviewing.

--  Simon Riggs              EnterpriseDB   http://www.enterprisedb.com