Chapter 44. PL/Python - Python Procedural Language

Table of Contents
44.1. Python 2 vs. Python 3
44.2. PL/Python Functions
44.3. Data Values
44.3.1. Data Type Mapping
44.3.2. Null, None
44.3.3. Arrays, Lists
44.3.4. Composite Types
44.3.5. Set-returning Functions
44.4. Sharing Data
44.5. Anonymous Code Blocks
44.6. Trigger Functions
44.7. Database Access
44.7.1. Database Access Functions
44.7.2. Trapping Errors
44.8. Explicit Subtransactions
44.8.1. Subtransaction Context Managers
44.8.2. Older Python Versions
44.9. Utility Functions
44.10. 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 44.1).

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.