Overview

GreptimeDB supports running Python script inside the database. If the business logic is too complex to express via SQL, you can use python. Python prevails in the data science and AI world. To avoid spending lots of time and effort transferring and transforming data, we provide the capability of executing Python scripts in the database.

We think the python scripts in GreptimeDB is a perfect replacement for stored procedures in traditional RDMS, and also the user can create SQL UDFs(User Defined Function).

• Getting started
• Function
• Query data
• Write data
• Data types
• API

All the examples can be found in python-coprocessor-examples.

Note

The Python scripts is currently in its experimental phase, and the API may undergo some changes.

You can download pre-built binaries with PyO3 supported whose file names are postfixed by pyo3.You can just also use RustPython which doesn’t require additional setup by download binary files without pyo3 postfixed.

If you have some library link issues, you must set up the correct Python shared library, which can be a bit challenging. In general, you just need to install the python-dev package(on most Debian-based system). However, if you are using Homebrew to install Python on macOS, you must create a proper soft link to Library/Frameworks/Python.framework. The recommended way is to utilize conda for managing your Python environment. Firstly, create a Python environment with the same version of Python demanded by the binary you download. Alternatively, you can employ a docker container and execute the greptime binary within it. A less recommended way is to manually install the exact version of Python required and set the LD_LIBRARY_PATH environment variable to the directory containing the libpython<VERSION>.so file. The version number of <VERSION> varies according to the version of Python being used.

There is two backends for Python Scripts:

1. RustPython Interpreter: this is supported without installing any Python library, but it is not as fast as CPython Backend. The Release Binary without pyo3 in its name uses RustPython Interpreter. While you can still use Python Syntax in RustPython Interpreter, you can’t use any third-parties libs.
2. CPython Interpreter: this is the most commonly used version of Python. It allows you to use all sorts of third-parties libs, but you need to install the correct Python shared library. Any Release Binary with pyo3 in its name uses CPython Interpreter.