For a mongo mapreduce flow, the emit function has the form emit(this.cId, {q1:this.Q1, q2s:this.Q2}); Choose the correct return value for the reduce function

Which field DBRefs has?

Which point describe when using embedded data models?

If the address data is frequently retrieved with the name information,how will you modify the following schema representing one to one relationship with referencing ? { _id: 'joe', name: 'Joe Bookreader' } { patron_id: 'joe', street: '123 Fake Street', city: 'Faketon', state: 'MA', zip: '12345' }

When should one should avoid embedding one document within another in MongoDB?

Point out the correct statement.

Which operator is related to geography of data ?

Sometimes the failover process may require a ____ during operation.

Consider the following posts collection in MongoDB, { '_id' : 1, 'post_title' : 'this is post title', 'tags': [ 'social', 'friends', 'books'], // rest of the document } Output of following query: db.posts.aggregate( [ { $unwind : '$tags' } ] )

Best describes the concept of Aggregations in MongoDB ?

Which aggregation option is used to specify the fields that need to be passed to the next stage of the aggregation pipeline?