On 7/30/06, Tom Lane <[EMAIL PROTECTED]> wrote:
"Sergey E. Koposov" <[EMAIL PROTECTED]> writes: > I see the very strange behaviour with the following set of queries:> wsdb=# select na,nb, na::double precision as da, nb::double precision as db from ( select random()::numeric as na,random()::numeric as nb from generate_series(1,2)) as xx; The planner "flattens" this query to a single level of SELECT, so what you effectively have is select random()::numeric as na, random()::numeric as nb, random()::numeric::double precision as da, random()::numeric::double precision as db from generate_series(1,2) as xx; There's been some talk about prohibiting flattening if there are any volatile functions in the subselect's targetlist, but nothing's been done about that. Disabling flattening is a sufficiently big hit to the planner's optimization ability that it shouldn't be done lightly. regards, tom lane
http://archives.postgresql.org/pgsql-hackers/2005-10/msg00396.php maybe a guc? -- regards, Jaime Casanova "Programming today is a race between software engineers striving to build bigger and better idiot-proof programs and the universe trying to produce bigger and better idiots. So far, the universe is winning." Richard Cook ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
