1.

You are an admin for MongoDB test database having sample collection. How can you export the contents of sample collection into CSV file?

Answer»

A query that is able to return entire results only by using the index is called a Covered Query. This is one of the optimization techniques that can be used with queries for faster RETRIEVAL of data. A query can be a covered query only if

  • all the fields in the query are part of an index and
  • all the fields that are RETURNED are also part of the same index

Since everything is part of the index, there is no need for the query to check the DOCUMENTS for any information.


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