MongoDB Interview Questions and Answers
Intermediate / 1 to 5 years experienced level questions & answers
Ques 1. What is indexing in MongoDB?
Indexing is the process of creating an index (like in a book) to improve the performance of queries. Indexes are used to quickly locate and access the data.
Ques 2. What is sharding in MongoDB?
Sharding is the process of distributing data across multiple servers. It is MongoDB's approach to meeting the demands of data growth.
Ques 3. Explain replication in MongoDB.
Replication is the process of synchronizing data across multiple servers. It provides redundancy and increases data availability.
Ques 4. What is the role of the profiler in MongoDB?
The profiler is a MongoDB feature that tracks queries executed against the database. It helps in analyzing and optimizing query performance.
Ques 5. How do you perform aggregation in MongoDB?
MongoDB provides the `aggregate` method to perform aggregation operations, such as filtering, grouping, sorting, and projecting data.
Ques 6. Explain the GridFS in MongoDB.
GridFS is a specification for storing and retrieving large files in MongoDB. It divides a file into chunks and stores each chunk as a separate document.
Ques 7. What is the TTL (Time To Live) index in MongoDB?
The TTL index is a special type of index that automatically deletes documents from a collection after a specified amount of time has passed.
Ques 8. How does MongoDB provide high availability?
MongoDB achieves high availability through replica sets, where data is replicated across multiple servers. If one server goes down, another can serve the data.
Ques 9. What is the role of the WiredTiger storage engine in MongoDB?
WiredTiger is the default storage engine in MongoDB. It provides features like compression, document-level locking, and support for multiple storage engines in the same MongoDB deployment.
Ques 10. What is the significance of the Journal in MongoDB?
The Journal in MongoDB is a write-ahead log that helps in recovering data in case of a server crash or failure. It ensures data durability and consistency.
Ques 11. Explain the process of data migration in MongoDB.
Data migration in MongoDB involves transferring data from one database or collection to another. It can be done using tools like `mongodump` and `mongorestore`.
Ques 12. How can you create an index in MongoDB?
You can create an index in MongoDB using the `createIndex` method. For example, `db.collection.createIndex({ field: 1 })` creates an ascending index on the specified field.
Ques 13. Explain the role of the `mongorestore` command in MongoDB.
The `mongorestore` command is used to restore MongoDB backups created with `mongodump`. It imports BSON data into a MongoDB database.
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