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This adds a new function, permute(), that generates pseudorandom permutations of arbitrary sizes. This can be used to randomly shuffle a set of values to remove unwanted correlations. For example, permuting the output from a non-uniform random distribution so that all the most common values aren't collocated, allowing more realistic tests to be performed. Formerly, hash() was recommended for this purpose, but that suffers from collisions that might alter the distribution, so recommend permute() for this purpose instead. Fabien Coelho and Hironobu Suzuki, with additional hacking be me. Reviewed by Thomas Munro, Alvaro Herrera and Muhammad Usama. Discussion: https://postgr.es/m/alpine.DEB.2.21.1807280944370.5142@lancre
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/.