Join two collections in MongoDB

Question

Am a beginner in mongoDB. I have two collections Book and author. [name and workswritten] are the common column respectively. Using inner join I have to emit the some columns in

Answer 1

MongoDB does not support JOIN operations. When you need this functionality, you have to implement it yourself by querying both collections.

For that reason it's often a good strategy to use embedding instead of linking.

A Map/Reduce job is usually a very expensive operation. It should only be used occasionally for data mining purposes.