How to set a primary key in MongoDB?

Question

I want to set one of my fields as primary key. I am using MongoDB as my NoSQL.

Answer 1

_id field is reserved for primary key in mongodb, and that should be a unique value. If you don't set anything to _id it will automatically fill it with "MongoDB Id Object". But you can put any unique info into that field.

Additional info: http://www.mongodb.org/display/DOCS/BSON

Hope it helps.