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If a view is defined atop another view, and then CREATE OR REPLACE VIEW is used to add columns to the lower view, then when the upper view's referencing RTE is expanded by ApplyRetrieveRule we will have a subquery RTE with fewer eref->colnames than output columns. This confuses various code that assumes those lists are always in sync, as they are in plain parser output. We have seen such problems before (cf commit d5b760ecb), and now I think the time has come to do what was speculated about in that commit: let's make ApplyRetrieveRule synthesize some column names to preserve the invariant that holds in parser output. Otherwise we'll be chasing this class of bugs indefinitely. Moreover, it appears from testing that this actually gives us better results in the test case d5b760ecb added, and likely in other corner cases that we lack coverage for. In HEAD, I replaced d5b760ecb's hack to make expandRTE exit early with an elog(ERROR) call, since the case is now presumably unreachable. But it seems like changing that in back branches would bring more risk than benefit, so there I just updated the comment. Per bug #17811 from Alexander Lakhin. Back-patch to all supported branches. Discussion: https://postgr.es/m/17811-d31686b78f0dffc9@postgresql.org
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/.