django-mongodb-engine/mongodb-engine — pull request #80 by maraujop (2011-11-01 09:14:07+00:00)
Title: Automatically create sparse indexes in unique and null fields

When you allow null in a unique field, you expect to be able to introduce several nulls in that column field. This generates the sparse indexes automatically. Otherwise you can forget to create the indexes and get bitten by it in the future.