For find queries, a cursor is created if and only if the results don't fit inside a single batch.

However, for agg queries it appears a cursor is always created regardless of whether or not a further batch is required. We should change this for agg to mirror find behavior to not waste an unnecessary cursor. 

Update:

• The default batch size is 101 docs or 16MB
• Walking through handleCursorCommand() could be a good starting point.
• Walking through how the find command does it is also a good starting point.