abe184101d
for the case that the semijoin was implemented within either input by unique-ifying its RHS before we test to see if it appears to match the current join situation. The previous coding would select semijoin logic in situations where we'd already unique-ified the RHS and joined it to some unrelated relation(s), and then came to join it to the semijoin's LHS. That still gave the right answer as far as the semijoin itself was concerned, but would lead to incorrectly examining only an arbitrary one of the matchable rows from the unrelated relation(s). The cause of this thinko was incorrect unification of the pre-8.4 logic for IN joins and OUTER joins --- the comparable case for outer joins can be handled after making the match test, but that's because there is nothing like the unique-ification escape hatch for outer joins. Per bug #4934 from Benjamin Reed.
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/.