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This was a bit disjointed, partly because of a not-well-considered decision to document SQL commands that don't return result rows as though they had nothing in common with commands that do. Rearrange so that we have one discussion of variable substitution that clearly applies to all types of SQL commands, and then handle the question of processing command output separately. Clarify that EXPLAIN, CREATE TABLE AS SELECT, and similar commands that incorporate an optimizable statement will act like optimizable statements for the purposes of variable substitution. Do a bunch of minor wordsmithing in the same area. David Johnston and Tom Lane, reviewed by Pavel Stehule and David Steele Discussion: https://postgr.es/m/CAKFQuwYvMKucM5fnZvHSo-ah4S=_n9gmKeu6EAo=_fTrohunqQ@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. PostgreSQL has many language interfaces, many of which are listed here: https://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. 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 https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.