MongoDB: Step-5: Indexes and Query Performance Optimizations
This covers the various options of indexes, how to evaluate the query, understand the query-plan and the usage of indexes for different business scenarios. MongoDB supports extensive feature indexes that enable rich querying. i.e. over and above the index on the primary key, it has the ability to index different columns as secondary indexes.
https://sarada-sastri.medium.com/mongodb-step-5-indexes-and-query-performance-optimizations-ed1bf744315b