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When reduce_outer_joins reduces an outer join to an antijoin, any IS NULL qual on a Var from the antijoin's nullable side is necessarily true. Previously, such quals were discarded later in distribute_qual_to_rels, mainly to avoid bogus selectivity estimates. But that discard was incomplete: the qual remained in the jointree, while its Vars were not counted in attr_needed. Since commit2ebf25e7d, join removal edits the jointree and expects it to contain no other references to a removed rel, so it could remove a rel that such a discarded qual still references, and then trip an assertion on the qual's stale Var. To fix, move this processing to an earlier phase: such quals are now removed from the jointree by reduce_outer_joins itself. This way later phases see a consistent query tree, and check_redundant_nullability_qual is no longer needed, so remove it. Back-patch to v16, as with commit2ebf25e7d. Reported-by: Tender Wang <tndrwang@gmail.com> Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/CAHewXNk8b0TsSy4dL=CO7FXL2W3WBm0BcdP-zwNJePa-Qj4HzA@mail.gmail.com Backpatch-through: 16
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/.