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Previously, when executing an ON UPDATE SET NULL or SET DEFAULT action for a multicolumn MATCH SIMPLE foreign key constraint, we would set only those referencing columns corresponding to referenced columns that were changed. This is what the SQL92 standard said to do --- but more recent versions of the standard say that all referencing columns should be set to null or their default values, no matter exactly which referenced columns changed. At least for SET DEFAULT, that is clearly saner behavior. It's somewhat debatable whether it's an improvement for SET NULL, but it appears that other RDBMS systems read the spec this way. So let's do it like that. This is a release-notable behavioral change, although considering that our documentation already implied it was done this way, the lack of complaints suggests few people use such cases.
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/.