Where can I read about such features?
2006/6/1, Martijn van Oosterhout <kleptog@xxxxxxxxx>:
On Thu, Jun 01, 2006 at 03:09:47PM +0400, Dan Black wrote:
> Hi
> I have a stable function test.test_stable
<snip>
> But if I want to display field sid twice
>
> SELECT id, sid, sid FROM
> (SELECT *, test.test_stable(id) AS sid FROM generate_series(10, 100) AS id)
> tbl
>
> I can see that function test.test_stable executes twice with identical
> parameters
Postgres makes no special effort to avoid multiple calls of the same
function. Especially since you declared it STABLE.
> Is it bug or special feature?
Not a bug nor a special feature, just the way it is. If you put OFFSET 0
in the subquery, that will stop the expansion of the subquery, thus the
function will only be called once.
Have a nice day,
--
Martijn van Oosterhout <kleptog@xxxxxxxxx> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.
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--
Verba volent, scripta manent
Dan Black
