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nodeAppend.c used non-nullness of appendstate->as_valid_subplans as a state flag to indicate whether it'd done ExecFindMatchingSubPlans (or some sufficient approximation to that). This was pretty questionable even in the beginning, since it wouldn't really work right if there are no valid subplans. It got more questionable after commit 27e1f1456 added logic that could reduce as_valid_subplans to an empty set: at that point we were depending on unspecified behavior of bms_del_members, namely that it'd not return an empty set as NULL. It's about to start doing that, which breaks this logic entirely. Hence, add a separate boolean flag to signal whether as_valid_subplans has been computed. Also fix a previously-cosmetic bug in nodeAgg.c, wherein it ignored the return value of bms_del_member instead of updating its pointer. Patch by me; thanks to Nathan Bossart and Richard Guo for review. Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
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/.