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When a rule action or rule qualification references NEW.col where col is a generated column (stored or virtual), the rewriter produces incorrect results. rewriteTargetListIU removes generated columns from the query's target list, since stored generated columns are recomputed by the executor and virtual ones store nothing. However, ReplaceVarsFromTargetList then cannot find these columns when resolving NEW references during rule rewriting. For UPDATE, the REPLACEVARS_CHANGE_VARNO fallback redirects NEW.col to the original target relation, making it read the pre-update value (same as OLD.col). For INSERT, REPLACEVARS_SUBSTITUTE_NULL replaces it with NULL. Both are wrong when the generated column depends on columns being modified. Fix by building target list entries for generated columns from their generation expressions, pre-resolving the NEW.attribute references within those expressions against the query's targetlist, and passing them together with the query's targetlist to ReplaceVarsFromTargetList. Back-patch to all supported branches. Virtual generated columns were added in v18, so the back-patches in pre-v18 branches only handle stored generated columns. Reported-by: SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com> Author: Richard Guo <guofenglinux@gmail.com> Author: Dean Rasheed <dean.a.rasheed@gmail.com> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://postgr.es/m/CAHg+QDexGTmCZzx=73gXkY2ZADS6LRhpnU+-8Y_QmrdTS6yUhA@mail.gmail.com Backpatch-through: 14
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/.