Which of the following 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.

Choose the best description of why MongoDB performs well on a non heterogeneous cluster:

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

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.