Re: [GENERAL] Stored procedures and "pseudo" fields..

On Tue, 20 Jul 2004 09:45:06 -0600, Scott Marlowe wrote:
> > Kinda like this:
> >
> > SELECT *, acl_check( objects.obid, ) AS mode FROM objects
> > WHERE mode > 0;
>
> Here's the problem. In order to do the select, the query first needs to
> run the where clause. I.e.:
>
> select a as test from table where a > 50;
>
> works, but
>
> select a as test from table where test > 50;
>
> fails. The reason is that when the where clause fires first, there IS
> no test yet, as it hasn't been materialized. what you need to do is:
>
> select custom_function(a,b) from table where custom_function(a,b) > 0;
>
>

Thanks for clearing that up. I just hoped there was some magic I could
sprinkle on my query to get away from the extra overhead of running
the procedure twice :)

Best regards..

L.E.Thorsplass

---------------------------(end of broadcast)---------------------------
TIP 7: don't forget to increase your free space map settings

Re: Stored procedures and "pseudo" fields

Lars Erik Thorsplass wrote:

> On Tue, 20 Jul 2004 09:45:06 -0600, Scott Marlowe wrote:
> > > Kinda like this:
> > >
> > > SELECT *, acl_check( objects.obid, ) AS mode FROM objects
> > > WHERE mode > 0;
> >
> > Here's the problem. In order to do the select, the query first needs to
> > run the where clause. I.e.:
> >
> > select a as test from table where a > 50;
> >
> > works, but
> >
> > select a as test from table where test > 50;
> >
> > fails. The reason is that when the where clause fires first, there IS
> > no test yet, as it hasn't been materialized. what you need to do is:
> >
> > select custom_function(a,b) from table where custom_function(a,b) > 0;
> >
> >
>
> Thanks for clearing that up. I just hoped there was some magic I could
> sprinkle on my query to get away from the extra overhead of running
> the procedure twice :)
>
> Best regards..
>
> L.E.Thorsplass
>

Pretty late, I know, but just for the record, AFAICS there is this magic as
SELECT * FROM (
SELECT *, acl_check( objects.obid, ) AS mode FROM objects
) AS foo WHERE mode > 0;

Regards, Christoph



---------------------------(end of broadcast)---------------------------
TIP 8: explain analyze is your friend