For a collection that represents type A { “field1” : “val1”, “field2” : “val2” } Choose the best way to optimize the collection for updates if field2 is an Enumeration.

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?

___ filters the document stream to allow only matching documents to pass unmodified into the next pipeline stage.

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 ?