From 1eeee69099e0402722457534df4744d8679bbe23 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/postgres_fdw.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'contrib/postgres_fdw/postgres_fdw.c') diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c index 04ce9e31053..54d4d3a4816 100644 --- a/contrib/postgres_fdw/postgres_fdw.c +++ b/contrib/postgres_fdw/postgres_fdw.c @@ -554,13 +554,16 @@ postgresGetForeignPaths(PlannerInfo *root, * baserestrict conditions we were able to send to remote, there might * actually be an indexscan happening there). We already did all the work * to estimate cost and size of this path. + * + * Although this path uses no join clauses, it could still have required + * parameterization due to LATERAL refs in its tlist. */ path = create_foreignscan_path(root, baserel, fpinfo->rows, fpinfo->startup_cost, fpinfo->total_cost, NIL, /* no pathkeys */ - NULL, /* no outer rel either */ + baserel->lateral_relids, NULL, /* no extra plan */ NIL); /* no fdw_private list */ add_path(baserel, (Path *) path); -- cgit v1.2.3