Horton

Re: ORDER BY pushdowns seem broken in postgres_fdw

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Ronan Dunklau <ronan.dunklau@aiven.io>
Cc: Ranier Vilela <ranier.vf@gmail.com>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Jeevan Chalke <jeevan.chalke@enterprisedb.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: 2021-07-22T07:44:54Z
Lists: pgsql-hackers 
On Thu, 22 Jul 2021 at 19:00, Ronan Dunklau <ronan.dunklau@aiven.io> wrote:
> Please find it reattached.

+-- This will not be pushed either
+explain verbose select * from ft2 order by c1 using operator(public.<^);
+                                  QUERY PLAN
+-------------------------------------------------------------------------------
+ Sort  (cost=190.83..193.33 rows=1000 width=142)


Can you also use explain (verbose, costs off) the same as the other
tests in that area.  Having the costs there would never survive a run
of the buildfarm. Different hardware will produce different costs, e.g
32-bit hardware might cost cheaper due to narrower widths.

History lesson: costs off was added so we could test plans. Before
that, I don't think that the regression tests had any coverage for
plans.  Older test files still likely lack much testing with EXPLAIN.

David

Commits

  1. Fix postgres_fdw to check shippability of sort clauses properly.

  2. postgres_fdw: Add ORDER BY to some remote SQL queries.