PostgreSQL includes several procedural
languages with the base distribution: PL/PgSQL, PL/Tcl,
PL/Perl, and PL/Python.
In addition, there are a number of procedural languages that are developed
and maintained outside the core PostgreSQL
distribution. Table H-2 lists some of these
packages. Note that some of these projects may not be released under the same
license as PostgreSQL. For more information on each
procedural language, including licensing information, refer to its website
and documentation.
Table H-2. Externally Maintained Procedural Languages