Retrieve records in mongoDB using bidirectional query

Question

I have two collections - Tickets and Users. Where a user can have one to many tickets. The ticket collection is defined as follows

Ticket = {_id, ownerId, profile: {name}}

The ownerId is used to find all tickets that belong to a specific person. I need to write a query that gets me all users with no tickets.

How can i write this query without having to loop through all users, checking if the userID shows up in any Tickets?

Would a bidirectional storage cause me any performance problems ? For example, if i were to change my users collection and add an array of tickets: [ticketID, ticketID2, ...]?

Answer 1

I'd go with the array of tickets being stored in users. As far as I know, Mongo doesn't really have a way to query one collection based on the (lack of) elements in another collection. With the array, though, you can simply do db.users.find({tickets:[]}).