Re: referring to computed values from the select list in the where and order clauses

On 2004.03.01 03:21 Richard Huxton wrote:
> On Monday 01 March 2004 01:04, Stephen Howard wrote:
> > I've got a moderately complex function defined which i then want to
> be
> >
> > able to test the value of, as well as select the value:
> >
> > select id, vector_cosine(document,'[ qw( foo,bar,baz )]') as
> threshold
> > from search_vectorspace where threshold > 0 order by threshold desc;
>
> However, you can mark functions as immutable/stable/volatile which can
> allow
> PG to cache the query results. See the manuals (CREATE FUNCTION) for
> details.

Depending on your requirements you may be able to store the results
in a temporary table CREATE TABLE TEMP ... ; INSERT INTO...

Don't know that this is a better alternative.

Karl <kop@meme.com>
Free Software:  "You don't pay back, you pay forward."
                  -- Robert A. Heinlein