At Euro DjangoCon I met lots of people and talked a lot about MongoDB as the backend. I even did a presentation on the subject which led to a lot of people asking me more questions about MongoDB.

I did mention to some people that one of the drawbacks of using MongoDB which doesn't have transactions is that you have to create and destroy the collections (like SQL tables) each time for every single test runs. I thought this was slow. It's not

Today I've been doing some more profiling and testing and debugging and I can conclude that it's not a problem. Creating the database has a slight delay but it's something you only have to do once and actually it's very fast. Here's how I tear down the collections in between each test:

class BaseTest(TestCase):

   def tearDown(self):
       for name in self.database.collection_names():
           if name not in ('system.indexes',):
               self.database.drop_collection(name)

For example, running test of one of my apps looks like this:

$ ./manage.py test myapp
...........lots.............
----------------------------------------------------------------------
Ran 55 tests in 3.024s

So, don't fear writing lots of individual unit tests. MongoDB will not slow you down.

Philip Gatt - 07 June 2012 [«« Reply to this]
I was dropping mongo databases and it was WAY too slow. Thanks for your post. This approach is much faster.


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