34ea1ab7fd
Up to now postgres_fdw has been using create_foreignscan_path() to generate not only base-relation paths, but also paths for foreign joins and foreign upperrels. This is wrong, because create_foreignscan_path() calls get_baserel_parampathinfo() which will only do the right thing for baserels. It accidentally fails to fail for unparameterized paths, which are the only ones postgres_fdw (thought it) was handling, but we really need different APIs for the baserel and join cases. In HEAD, the best thing to do seems to be to split up the baserel, joinrel, and upperrel cases into three functions so that they can have different APIs. I haven't actually given create_foreign_join_path a different API in this commit: we should spend a bit of time thinking about just what we want to do there, since perhaps FDWs would want to do something different from the build-up-a-join-pairwise approach that get_joinrel_parampathinfo expects. In the meantime, since postgres_fdw isn't prepared to generate parameterized joins anyway, just give it a defense against trying to plan joins with lateral refs. In addition (and this is what triggered this whole mess) fix bug #15613 from Srinivasan S A, by teaching file_fdw and postgres_fdw that plain baserel foreign paths still have outer refs if the relation has lateral_relids. Add some assertions in relnode.c to catch future occurrences of the same error --- in particular, to catch other FDWs doing that, but also as backstop against core-code mistakes like the one fixed by commit bdd9a99aa. Bug #15613 also needs to be fixed in the back branches, but the appropriate fix will look quite a bit different there, since we don't want to assume that existing FDWs get the word right away. Discussion: https://postgr.es/m/15613-092be1be9576c728@postgresql.org
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.