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When a join has an alias, the parser marks every Var referenced through that alias with the join's RT index as its syntactic referent (varnosyn), even though varno points at the underlying base relation. Since commit2ebf25e7d, join removal strips the removed relids from the query tree using ChangeVarNodes() with INVALID_VAR, which asserts that the relid doesn't appear in any field identifying a single relation. A varnosyn that names the removed join violates that, so a query like SELECT j.x FROM (t1 s(x) LEFT JOIN t2 ON s.x = t2.a) j; with t2.a unique fails an assertion. In non-assert builds, varnosyn is silently set to INVALID_VAR. Such syntactic references are still valid after the removal: the join is only taken out of the jointree, and its RTE remains in the rangetable through to the finished plan. So, when deleting a relid, leave varnosyn unchanged, as join removal did before2ebf25e7d. Back-patch to v16, as with commit2ebf25e7d. Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/CAMbWs484SQSdzWTgZYKvwtuC6J4m7acw0LfBjp3aWPvav7gC_w@mail.gmail.com Backpatch-through: 16
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/.