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

Best describes the concept of Aggregations in MongoDB ?

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' } ] )

Sometimes the failover process may require a ____ during operation.

Which operator is related to geography of data ?

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

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

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' }

Which point describe when using embedded data models?

Which field DBRefs has?

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