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As part of upper planner pathification (commit 3fc6e2d7f5b652b4) I redid createplan.c's approach to the physical-tlist optimization, in which scan nodes are allowed to return exactly the underlying table's columns so as to save doing a projection step at runtime. The logic was intentionally more aggressive than before about applying the optimization, which is generally a good thing, but Andres Freund found a case in which it got too aggressive. Namely, if any column is referenced more than once in the parent plan node's sorting or grouping column list, we can't optimize because then that column would need to have more than one ressortgroupref label, and we only have space for one. Add logic to detect this situation in use_physical_tlist(), and also add some error checking in apply_pathtarget_labeling_to_tlist(), which this example proves was being overly cavalier about whether what it was doing made any sense. The added test case exposes the problem only because we do not eliminate duplicate grouping keys. That might be something to fix someday, but it doesn't seem like appropriate post-beta work. Report: <20160526021235.w4nq7k3gnheg7vit@alap3.anarazel.de>
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/.