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ORDER BY expressions were being treated the same as regular aggregate arguments for purposes of collation determination, but really they should not affect the aggregate's collation at all; only collations of the aggregate's regular arguments should affect it. In many cases this mistake would lead to incorrectly throwing a "collation conflict" error; but in some cases the corrected code will silently assign a different collation to the aggregate than before, for example agg(foo ORDER BY bar COLLATE "x") which will now use foo's collation rather than "x" for the aggregate. Given this risk and the lack of field complaints about the issue, it doesn't seem prudent to back-patch. In passing, rearrange code in assign_collations_walker so that we don't need multiple copies of the standard logic for computing collation of a node with children. (Previously, CaseExpr duplicated the standard logic, and we would have needed a third copy for Aggref without this change.) Andrew Gierth and David Fetter
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. Changes between all PostgreSQL releases are recorded in the file HISTORY. 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/.