Describe the best use case for choosing MongoDB map-reduce.

What is the minimum nodes required for replica?

Which is correct index types?

Given the below statement, please choose the most probable reason:- 'You have a web application with mongodb as a backend. A query returns a resultset, however when called a second time the result set is empty.'

Choose the type of query where indexes can result in slower query response time.

For the query below db.collection.find( { x: 5 } ).sort( { z: 1} ) Choose the best index to support the query

Regarding aggregation pipeline optimization concepts in MongoDB, if you have a $sort followed by a $match:

Regarding storage in MongoDB, which is incorrect?

What is the maximum size of an Index key?

What is the maximum number of Indexes per collection allowed?

Best statement that describes: 'why aggregation queries outperform mapreduce for small datasets'.