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When we shoehorned "x op ANY (array)" into the SQL syntax, we created a fundamental ambiguity as to the proper treatment of a sub-SELECT on the righthand side: perhaps what's meant is to compare x against each row of the sub-SELECT's result, or perhaps the sub-SELECT is meant as a scalar sub-SELECT that delivers a single array value whose members should be compared against x. The grammar resolves it as the former case whenever the RHS is a select_with_parens, making the latter case hard to reach --- but you can get at it, with tricks such as attaching a no-op cast to the sub-SELECT. Parse analysis would throw away the no-op cast, leaving a parsetree with an EXPR_SUBLINK SubLink directly under a ScalarArrayOpExpr. ruleutils.c was not clued in on this fine point, and would naively emit "x op ANY ((SELECT ...))", which would be parsed as the first alternative, typically leading to errors like "operator does not exist: text = text[]" during dump/reload of a view or rule containing such a construct. To fix, emit a no-op cast when dumping such a parsetree. This might well be exactly what the user wrote to get the construct accepted in the first place; and even if she got there with some other dodge, it is a valid representation of the parsetree. Per report from Karl Czajkowski. He mentioned only a case involving RLS policies, but actually the problem is very old, so back-patch to all supported branches. Report: <20160421001832.GB7976@moraine.isi.edu> |
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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: http://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 http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.