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This fixes a bug that, under some circumstances, would cause MERGE to fail to properly recompute expressions for GENERATED STORED columns. Formerly, ExecInitModifyTable() did not call ExecInitStoredGenerated() for a MERGE command, which meant that the generated expressions information was not computed until later, when the first merge action was executed. However, if the first merge action to execute was an UPDATE, then ExecInitStoredGenerated() could decide to skip some some generated columns, if the columns on which they depended were not updated, which was a problem if the MERGE also contained an INSERT action, for which no generated columns should be skipped. So fix by having ExecInitModifyTable() call ExecInitStoredGenerated() for MERGE, and assume that it isn't safe to skip any generated columns in a MERGE. Possibly that could be relaxed, by allowing some generated columns to be skipped for a MERGE without an INSERT action, but it's not clear that it's worth the effort. Noticed while investigating bug #17759. Back-patch to v15, where MERGE was added. Dean Rasheed, reviewed by Tom Lane. Discussion: https://postgr.es/m/17759-e76d9bece1b5421c%40postgresql.org https://postgr.es/m/CAEZATCXb_ezoMCcL0tzKwRGA1x0oeE%3DawTaysRfTPq%2B3wNJn8g%40mail.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/.