On Sun, 18 Oct 2009, Tom Lane wrote:
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.
Thnx Tom. It also works without the OFFSET kludge. Any ideas why?
Looks also reasonable to me because there is no SETOF returned.
BTW: Why is the function in the original statement evaluated twice? On
"SELECT table.*" I guess query is also executed once and not n times (for
each column).
PG is version 8.3.8.
Thnx.
Ciao,
Gerhard
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