Re: ORDER BY pushdowns seem broken in postgres_fdw - Mailing list pgsql-hackers

From Zhihong Yu
Subject Re: ORDER BY pushdowns seem broken in postgres_fdw
Date
Msg-id CALNJ-vQiJ8RsCjZXJiWcTHQjSjdMGrZQ5mV+2KSCjO9NoWOxSQ@mail.gmail.com
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In response to Re: ORDER BY pushdowns seem broken in postgres_fdw  (Ronan Dunklau <ronan@dunklau.fr>)
Responses Re: ORDER BY pushdowns seem broken in postgres_fdw
List pgsql-hackers


On Mon, Sep 6, 2021 at 1:17 AM Ronan Dunklau <ronan@dunklau.fr> wrote:
Le vendredi 3 septembre 2021, 22:54:25 CEST David Zhang a écrit :
> The following review has been posted through the commitfest application:
> make installcheck-world:  tested, failed
> Implements feature:       tested, passed
> Spec compliant:           not tested
> Documentation:            not tested
>
> Applied the v6 patch to master branch and ran regression test for contrib,
> the result was "All tests successful."

What kind of error did you get running make installcheck-world ? If it passed
the make check for contrib, I can't see why it would fail running make
installcheck-world.

In any case, I just checked and running make installcheck-world doesn't
produce any error.

Since HEAD had moved a bit since the last version, I rebased the patch,
resulting in the attached v7.

Best regards,

--
Ronan Dunklau
Hi,
bq. a pushed-down order by could return wrong results. 

Can you briefly summarize the approach for fixing the bug in the description ?

+ * Returns true if it's safe to push down a sort as described by 'pathkey' to
+ * the foreign server
+ */
+bool
+is_foreign_pathkey(PlannerInfo *root,

It would be better to name the method which reflects whether pushdown is safe. e.g. is_pathkey_safe_for_pushdown.

Cheers

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