On 6/5/21 14:11, Etsuro Fujita wrote:
On Tue, Apr 27, 2021 at 3:57 PM Andrey V. Lepikhov
<a.lepik...@postgrespro.ru> wrote:
One more question. Append choose async plans at the stage of the Append
plan creation.
Later, the planner performs some optimizations, such as eliminating
trivial Subquery nodes. So, AsyncAppend is impossible in some
situations, for example:
(SELECT * FROM f1 WHERE a < 10)
UNION ALL
(SELECT * FROM f2 WHERE a < 10);
But works for the query:
SELECT *
FROM (SELECT * FROM f1 UNION ALL SELECT * FROM f2) AS q1
WHERE a < 10;
As far as I understand, this is not a hard limit.
I think so, but IMO I think this would be an improvement rather than a bug fix.
We can choose async
subplans at the beginning of the execution stage.
For a demo, I prepared the patch (see in attachment).
It solves the problem and passes the regression tests.
Thanks for the patch! IIUC, another approach to this would be the
patch you proposed before [1]. Right?
Yes. I think, new solution will be better.
--
regards,
Andrey Lepikhov
Postgres Professional
