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This adds a new ALTER TABLE subcommand ALTER COLUMN ... SET EXPRESSION that changes the generation expression of a generated column. The syntax is not standard but was adapted from other SQL implementations. This command causes a table rewrite, using the usual ALTER TABLE mechanisms. The implementation is similar to and makes use of some of the infrastructure of the SET DATA TYPE subcommand (for example, rebuilding constraints and indexes afterwards). The new command requires a new pass in AlterTablePass, and the ADD COLUMN pass had to be moved earlier so that combinations of ADD COLUMN and SET EXPRESSION can work. Author: Amul Sul <sulamul@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAAJ_b94yyJeGA-5M951_Lr+KfZokOp-2kXicpmEhi5FXhBeTog@mail.gmail.com
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. Copyright and license information can be found in the file COPYRIGHT. General documentation about this version of PostgreSQL can be found at: https://www.postgresql.org/docs/devel/ In particular, information about building PostgreSQL from the source code can be found at: https://www.postgresql.org/docs/devel/installation.html The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.