Chapter 43. PL/Python - Python Procedural Language

Table of Contents
43.1. Python 2 vs. Python 3
43.2. PL/Python Functions
43.3. Data Values
43.3.1. Data Type Mapping
43.3.2. Null, None
43.3.3. Arrays, Lists
43.3.4. Composite Types
43.3.5. Set-returning Functions
43.4. Sharing Data
43.5. Anonymous Code Blocks
43.6. Trigger Functions
43.7. Database Access
43.7.1. Database Access Functions
43.7.2. Trapping Errors
43.8. Explicit Subtransactions
43.8.1. Subtransaction Context Managers
43.8.2. Older Python Versions
43.9. Utility Functions
43.10. Environment Variables

The PL/Python procedural language allows PostgreSQL functions to be written in the Python language.

To install PL/Python in a particular database, use CREATE EXTENSION plpythonu, or from the shell command line use createlang plpythonu dbname (but see also Section 43.1).

Tip: If a language is installed into template1, all subsequently created databases will have the language installed automatically.

PL/Python is only available as an "untrusted" language, meaning it does not offer any way of restricting what users can do in it and is therefore named plpythonu. A trusted variant plpython might become available in the future if a secure execution mechanism is developed in Python. The writer of a function in untrusted PL/Python must take care that the function cannot be used to do anything unwanted, since it will be able to do anything that could be done by a user logged in as the database administrator. Only superusers can create functions in untrusted languages such as plpythonu.

Note: Users of source packages must specially enable the build of PL/Python during the installation process. (Refer to the installation instructions for more information.) Users of binary packages might find PL/Python in a separate subpackage.