From 9d6d2b21343db76a769fbcae72fbcbc18aa388cb Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 7 Feb 2019 13:10:46 -0500 Subject: Ensure that foreign scans with lateral refs are planned correctly. As reported in bug #15613 from Srinivasan S A, file_fdw and postgres_fdw neglected to mark plain baserel foreign paths as parameterized when the relation has lateral_relids. Other FDWs have surely copied this mistake, so rather than just patching those two modules, install a band-aid fix in create_foreignscan_path to rectify the mistake centrally. Although the band-aid is enough to fix the visible symptom, correct the calls in file_fdw and postgres_fdw anyway, so that they are valid examples for external FDWs. Also, since the band-aid isn't enough to make this work for parameterized foreign joins, throw an elog(ERROR) if such a case is passed to create_foreignscan_path. This shouldn't pose much of a problem for existing external FDWs, since it's likely they aren't trying to make such paths anyway (though some of them may need a defense against joins with lateral_relids, similar to the one this patch installs into postgres_fdw). Add some assertions in relnode.c to catch future occurrences of the same error --- in particular, as backstop against core-code mistakes like the one fixed by commit bdd9a99aa. Discussion: https://postgr.es/m/15613-092be1be9576c728@postgresql.org --- contrib/postgres_fdw/sql/postgres_fdw.sql | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'contrib/postgres_fdw/sql/postgres_fdw.sql') diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index cef42d26f19..813286bba5f 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -884,6 +884,32 @@ select c2, sum from "S 1"."T 1" t1, lateral (select sum(t2.c1 + t1."C 1") sum fr select c2, sum from "S 1"."T 1" t1, lateral (select sum(t2.c1 + t1."C 1") sum from ft2 t2 group by t2.c1) qry where t1.c2 * 2 = qry.sum and t1.c2 < 3 and t1."C 1" < 100 order by 1; reset enable_hashagg; +-- bug #15613: bad plan for foreign table scan with lateral reference +EXPLAIN (VERBOSE, COSTS OFF) +SELECT ref_0.c2, subq_1.* +FROM + "S 1"."T 1" AS ref_0, + LATERAL ( + SELECT ref_0."C 1" c1, subq_0.* + FROM (SELECT ref_0.c2, ref_1.c3 + FROM ft1 AS ref_1) AS subq_0 + RIGHT JOIN ft2 AS ref_3 ON (subq_0.c3 = ref_3.c3) + ) AS subq_1 +WHERE ref_0."C 1" < 10 AND subq_1.c3 = '00001' +ORDER BY ref_0."C 1"; + +SELECT ref_0.c2, subq_1.* +FROM + "S 1"."T 1" AS ref_0, + LATERAL ( + SELECT ref_0."C 1" c1, subq_0.* + FROM (SELECT ref_0.c2, ref_1.c3 + FROM ft1 AS ref_1) AS subq_0 + RIGHT JOIN ft2 AS ref_3 ON (subq_0.c3 = ref_3.c3) + ) AS subq_1 +WHERE ref_0."C 1" < 10 AND subq_1.c3 = '00001' +ORDER BY ref_0."C 1"; + -- Check with placeHolderVars explain (verbose, costs off) select sum(q.a), count(q.b) from ft4 left join (select 13, avg(ft1.c1), sum(ft2.c1) from ft1 right join ft2 on (ft1.c1 = ft2.c1)) q(a, b, c) on (ft4.c1 <= q.b); -- cgit v1.2.3