
The JOIN_SEMI case Assert'ed that there are no PlaceHolderVars that need to be evaluated at the semijoin's RHS, which is wrong because there could be some in the semijoin's qual condition. However, there could not be any references further up than that, and within the qual there is not any way that such a PHV could have gone to null yet, so we don't really need the PHV and there is no need to avoid making the RHS-removal optimization. The upshot is that there's no actual bug in production code, and we ought to just remove this misguided Assert. While we're here, also drop the JOIN_RIGHT case, which is dead code because reduce_outer_joins() already got rid of JOIN_RIGHT. Per bug #17700 from Xin Wen. Uselessness of the JOIN_RIGHT case pointed out by Richard Guo. Back-patch to v12 where this code was added. Discussion: https://postgr.es/m/17700-2b5c10d917c30687@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/.
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