Using maxTimeMS parameter with aggregation queries on Mongo 2.6 and Pymongo 2.7.1

Question

• I'm unable to use maxTimeMS parameter with Mongo 2.6 and Pymongo 2.7.1

• As per the documentation on this page Official Mongodb Aggregation Page the aggregation method should return a Cursor object. However, when I run the query locally on a mongod instance (2.6+) with pymongo 2.7.1, I get a dict object!

In [14]: obj = coll.aggregate({'$group': {'_id': '$l', 'n': {'$sum': 1}}})

In [15]: type(obj) Out[15]: dict

Can anyone help me understand what is happening here?

Answer 1

Yes, you can use maxTimeMS with pymongo aggregation.

c.foo.bar.aggregate([], maxTimeMS=1000)
{u'ok': 1.0, u'result': []}

If you want a cursor:

for result in c.foo.bar.aggregate([], cursor={}, maxTimeMS=1000):
... print result

The aggregate command didn't support cursors before MongoDB 2.6 so it had to be added as an option to avoid breaking existing applications.