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';

Result:

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