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This means that they can initially be added to a large existing table without checking its initial contents, but new tuples must comply to them; a separate pass invoked by ALTER TABLE / VALIDATE can verify existing data and ensure it complies with the constraint, at which point it is marked validated and becomes a normal part of the table ecosystem. An non-validated CHECK constraint is ignored in the planner for constraint_exclusion purposes; when validated, cached plans are recomputed so that partitioning starts working right away. This patch also enables domains to have unvalidated CHECK constraints attached to them as well by way of ALTER DOMAIN / ADD CONSTRAINT / NOT VALID, which can later be validated with ALTER DOMAIN / VALIDATE CONSTRAINT. Thanks to Thom Brown, Dean Rasheed and Jaime Casanova for the various reviews, and Robert Hass for documentation wording improvement suggestions. This patch was sponsored by Enova Financial.
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/.