Experimental MySQL UDF code partially written in Python

Hi dear all,
I would like to share our experimental tests about, writing UDF with Python.
So the basic idea was writing a UDF for factorial calculation. The interesting part was to move factorial calculation logic to Python code and then calling this Python file inside UDF code.

Here is the repo link -> UDFs-written-in-Python

The factorial calculation is here -> factorial.py
UDF code is here -> factorial.cc

Basic idea with UDF code quite simple as it has 3 parts:
1. initialization part -> factorial_init() -> all necessary checks reside here
2. main logic -> factorial() -> calling Python script, reading data back and showing the result.
3. deinitialization -> factorial_deinit()

Compiled as:

gcc $(/home/sh/REPOS/MYSQL_DEV_ACTIONS/mysql-5.7/mysql-server/5.7.16/bin/mysql_config --cflags) -fPIC -shared -o factorial.so factorial.cc -std=c++11

Copied to plugin_dir:

cp factorial.so /home/sh/REPOS/MYSQL_DEV_ACTIONS/mysql-5.7/mysql-server/5.7.16/lib/plugin/
cp factorial.py /home/sh/REPOS/MYSQL_DEV_ACTIONS/mysql-5.7/mysql-server/5.7.16/lib/plugin/

Activated as:
mysql > create function factorial returns integer soname 'factorial.so';


root@test1:~# python --version
Python 2.7.12
mysql> select factorial(5);
| factorial(5) |
| 120 |
1 row in set (0.02 sec)

Author: Shahriyar Rzayev

Azerbaijan MySQL User Group and Python user group leader. QA Engineer, bug hunter by nature and true Pythonista

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