PostgreSQL

The PostgreSQL language named plpython2u implements PL/Python based on the Python 2 language variant.

The PostgreSQL language named plpython3u implements PL/Python based on the Python 3 language variant.

The language named plpythonu implements PL/Python based on the default Python language variant, which is currently Python 2. (This default is independent of what any local Python installations might consider to be their “[.quote]#default”#, for example, what /usr/bin/python might be.) The default will probably be changed to Python 3 in a distant future release of PostgreSQL, depending on the progress of the migration to Python 3 in the Python community.

Existing users and users who are currently not interested in Python 3 use the language name plpythonu and don’t have to change anything for the foreseeable future. It is recommended to gradually “[.quote]#future-proof”# the code via migration to Python 2.6/2.7 to simplify the eventual migration to Python 3.

Users who know that they have heavily Python 2 dependent code and don’t plan to ever change it can make use of the plpython2u language name. This will continue to work into the very distant future, until Python 2 support might be completely dropped by PostgreSQL.

Users who want to dive into Python 3 can use the plpython3u language name, which will keep working forever by today’s standards. In the distant future, when Python 3 might become the default, they might like to remove the “[.quote]#3”# for aesthetic reasons.

Daredevils, who want to build a Python-3-only operating system environment, can change the contents of pg_pltemplate to make plpythonu be equivalent to plpython3u, keeping in mind that this would make their installation incompatible with most of the rest of the world.