How does Trello store data in MongoDB? (Collection per board?)

Question

How does Trello store their data (cards) in MongoDB?

I read ( How does Trello show history so quickly? ) that their Actions collection is the largest one. Thus I assume that they do not store all cards in one gigantic collection.

The only other logical solution seems a collection per board or per user. But they have a lot of users and I read ( http://www.mongodb.org/display/DOCS/Using+a+Large+Number+of+Collections ) that there is a limit on the number of collections and some people advise against using a lot of collections.

I hope someone from Trello team will answear this AND I hope to get some ideas on solving this kind of a problem also from the general community.

Answer 1

Trello stores all of the cards in one collection. The collection is sharded on the card's board id.