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To distinguish SQL statements that are INSERT/UPDATE/DELETE from other ones, exec_stmt_execsql looked at the post-rewrite form of the statement rather than the original. This is problematic because it did that only during first execution of the statement (in a session), but the correct answer could change later due to addition or removal of DO INSTEAD rules during the session. That could lead to an Assert failure, as reported by Tushar Ahuja and Robert Haas. In non-assert builds, there's a hazard that we would fail to enforce STRICT behavior when we'd be expected to. That would happen if an initially present DO INSTEAD, that replaced the original statement with one of a different type, were removed; after that the statement should act "normally", including strictness enforcement, but it didn't. (The converse case of enforcing strictness when we shouldn't doesn't seem to be a hazard, as addition of a DO INSTEAD that changes the statement type would always lead to acting as though the statement returned zero rows, so that the strictness error could not fire.) To fix, inspect the original form of the statement not the post-rewrite form, making it valid to assume the answer can't change intra-session. This should lead to the same answer in every case except when there is a DO INSTEAD that changes the statement type; we will now set mod_stmt=true anyway, while we would not have done so before. That breaks the Assert in the SPI_OK_REWRITTEN code path, which expected the latter behavior. It might be all right to assert mod_stmt rather than !mod_stmt there, but I'm not entirely convinced that that'd always hold, so just remove the assertion altogether. This has been broken for a long time, so back-patch to all supported branches. Discussion: https://postgr.es/m/CA+TgmoZUrRN4xvZe_BbBn_Xp0BDwuMEue-0OyF0fJpfvU2Yc7Q@mail.gmail.com
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/.