Question

I have a program query data from database (MySQL) every minute.

while 1:
    self.alerteng.updateAndAnalyze()
    time.sleep(60)

but the data doesn’t change frequently; maybe once an hour or a day.(change by another C++ program)

I think the best way is track the change if a change happens then I query and update my data.

any advice?

Answer 1

It depends what you’re doing, but SQLAlchemy’s Events functionality might help you out.

It lets you run code whenever something happens in your database, i.e. after you insert a new row, or set a column value. I’ve used it in Flask apps to kick off notifications or other async processes.

http://docs.sqlalchemy.org/en/rel_0_7/orm/events.html#mapper-events

Here’s toy code from a Flask app that’ll run the kick_off_analysis() function whenever a new YourModel model is created in the database.

from sqlalchemy import event

@event.listens_for(YourModel, "after_insert")
def kick_off_analysis(mapper, connection, your_model):
  # do stuff here

Hope that helps you get started.