MongoDB query based on count of embedded document

Question

Suppose I have:

Order: {_id: ..., items: [...]}

How to filter orders which have item number greater than 5?

Answer 1

To see if the length is greater than 5, you can test if a 6th element exists:

db.orders.find({"items.6": {$exists: true}})

This is much more efficient than using $where.