How do I index a database column

Question

Hopefully, I can get answers for each database server.

For an outline of how indexing works check out: How does database indexing work?

Answer 1

Since most of the answers are given for SQL databases, I am writing this for NOSQL databases, specifically for MongoDB.

Below is the syntax to create an index in the MongoDB using mongo shell.

db.collection.createIndex( ,  )

example - db.collection.createIndex( { name: -1 } )

In the above example an single key descending index is created on the name field.

Keep in mind MongoDB indexes uses B-tree data structure.

There are multiple types of indexes we can create in mongodb, for more information refer to below link - https://docs.mongodb.com/manual/indexes/