Re: Function returning 2 columns evaluated twice when both columns are needed

[Tom Lane <tgl@xxxxxxxxxxxxx>]

Gerhard Wiesinger <lists@xxxxxxxxxxxxx> writes:
> Since getSums() is a cursor and is complex and takes long time getSums 
> should only be evaluated once. Is there a better solution available to 
> get both columns from the function in the select?

You need a sub-select, along the lines of

SELECT
  cur_date,
  (gs).sum_m1,
  (gs).sum_m2
  FROM
  (
   SELECT
     cur_date,
     getSums(start_ts, stop_ts) AS gs
   FROM
     getDatesTimestamps($1, $2)
   OFFSET 0
  ) AS ss
   ;

The OFFSET bit is a kluge, but is needed to keep the planner from
flattening the subquery and undoing your work.

			regards, tom lane

-- 
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general