[{"collection":"user","count":5,"content":{"A":{"type":"enum","values":[1,2,3,4,5]},"B":{"type":"enum","values":[50,75,150,200,1000]}},"indexes":[{"name":"a_1_b_1","key":{"A":1,"B":1}}]}]

db.user.aggregate([{$match:{B:{$gt:100}}},{$sort:{A:1}},{$limit:1000}]).explain()