Consider the following posts collection in MongoDB, { "_id" : 1, "post_title" : "this is post title", "tags": [ "social", "friends", "books"], // rest of the document } What will be the 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:

Which operation on a single document will operate atomically?

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.

Which is captured by the Database Profiler in MongoDB ?