How to execute Python function when value in SQL table changes?

Question

I am having trouble finding this answer anywhere on the internet. I want to be able to monitor a row in a MySQL table for changes and when this occurs, run a Python function. This Python function I want to run has nothing to do with MySQL; it just enables a pin on a Raspberry Pi. I have tried looking into SQLAlchemy; however, I can't tell if it is a trigger or a data mapping. Is something like this even possible?

Thanks in advance!

Why not use pull instead of push? if this is a specific row, just query it for changes every X minutes/seconds. If these could be many rows, create a flag table and add UPDATE triggers to alter the flag there, and your python application will poll for changes and set the flag back... — van
– van, Commented Apr 9, 2013 at 20:02

Omar · Accepted Answer · 2013-04-09 14:31:39Z

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What about a cron job instead of create a loop? I think it's a bit nicer.

answered Apr 9, 2013 at 14:31

Omar

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Community · Accepted Answer · 2017-05-23 10:30:31Z

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make a loop which keeps checking the value of that row in MySQL table,the moment the value changes, call the function you want to execute. you can also refer to python: how to get notifications for mysql database changes?

edited May 23, 2017 at 10:30

CommunityBot

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answered Apr 9, 2013 at 13:39

scottydelta

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4 Comments

Ryan F Over a year ago

It sounds like UDF is the only way to do it. I just don't really want to make a loop because it seems like it could really burden the database with overhead. I was hoping to make it check more intelligently. My inspiration is kinda like Dropbox. It only syncs when it gets changes.

Brad Over a year ago

If all you are doing is select my_column from my_table where ... you're not really burdening the DB

Ryan F Over a year ago

Really? If that is true, this is a simple solution.

scottydelta Over a year ago

user2112825 is right, because MySQL has been designed to handle a large number of operations simultaneously, this would hardly affect the functioning of your database.

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