Added batch size option to the management command for populating the history

[mikeengland]

Currently, if you try and populate the history of a large table Django raises a 'lost connection to MySQL server' error. This is because the bulk_create method is not given a batch size.

This pull request adds an additional parameter to the management command (--batchsize), where you can specify this e.g. 500. I have set the default value to a reasonable 200. Issue #202 and #189 should be fixed in this pull request.

[codecov-io]

Current coverage is 96.85% (diff: 100%)

Merging #231 into master will not change coverage

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[mikeengland]

Hmm... looks like some of the TravisCI builds have failed due to the error OperationalError: no such table: tests_historicaltrackedwithmultipleabstractbases. Has anyone seen this before? (I'm not too familiar with SQL Lite).

[macro1]

Yes, I've seen errors like this before. There are some race conditions that can surface because we're dynamically creating models within some of the tests.

The table giving you trouble here is correctly missing... I'm not sure why Django thinks it should exist though. Here's the code in the tests: https://github.com/treyhunner/django-simple-history/blob/1.8.1/simple_history/tests/tests/test_models.py#L801

Of course these errors don't have anything to do with your change, or shouldn't. I can look at them later.

[mikeengland]

Ok, thanks @macro1 !

[mikeengland]

Please can someone take a look at merging this? It would be very useful to have in master.