Sort by particular field rather than key


- I have the documents which has 'order' field. I have to get all records sort by order field.
- User id 3 has more document like below, each has 'order'. Now i want to get all documents by the userId with sort by order. Now i could get all documents of userId is 3.

    "id": "62188fb9-cd02-4268-8a8c-17357f9a7b45",
    "order": 2,
    "userId" : 3

Map function:

emit(doc.userId, null);