Home Interview Questions Top 20 MongoDB Interview Questions and Answers

Top 20 MongoDB Interview Questions and Answers


Following are frequently asked questions of MongoDB in interviews for freshers as well as an experienced developer.

1) Explain MongoDB what is it?

Mongo-DB is a database of documents that delivers high efficiency, high availability and simple scalability.

2) What is MongoDB’s “Namespace?”

MongoDB shops objects from the set of BSON (Binary Interchange and Structure Object Notation). The name of the set and the name of the database is called a namespace.


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3) What’s MongoDB sharding?

Sharding is the method for storing data records across various computers. To satisfy the requirements of information development, it is a MongoDB strategy. In a database or search engine, it is the horizontal partition of information. Each partition is referred to as shard or shard from the database.

4) How do you see the Mongos link?

Use DB admin command (“connPoolStats”) to view the link used by Mongo.

5) Explain what is a replica set?

A set of replicas is a group of instances of mongo hosting the same set of data. One node is primary in the replica set, and another is secondary. All replicates of information from the primary to the secondary node.

6) How does MongoDB replicate?

The method of information synchronization is known as replication across various servers. It offers redundancy and increases the accessibility of information on various database servers with various copies of information. Replication helps protect the database against a single server’s loss.

7) While generating MongoDB Schema, what points should be taken into account?

Points must be taken into account when designing your schema according to user requirements If you use them together, combine items into one document. If not, distinguish them.
Join while you’re writing, not when you’re reading.
Optimize your schema for most common use instances.
Do complicated schema aggregation.

8) What is the syntax for creating a collection and dropping a MongoDB collection?

The db.createCollection(name,options) syntax for creating a collection in MongoDB.
The db.collection.drop) (syntax for dropping collection in MongoDB.

9) Explain what is Mongo’s role as a profiler?

MongoDB database profiler displays performance properties against the database for each procedure. Using the profiler you can discover queries which are slower than they should be.

10) Can you explain how to transfer ancient documents in the folder of moveChunk?

Yes, old files can be moved in the movingChunk directory, these files are made as backups during normal shard balancing operations and can be deleted once the operations are done.

11) What is the function you can use in Mongo to make secure backups?

Journaling is the function you can use to make secure backups in MongoDB.

12) What is Objecld made up of?

Objectld consists of Timestamp, client ID client process ID, 3 bytes incremented counter

13) Mention what is the syntax of the instruction to insert a document?

Database.collection.insert (document) is used to insert a document command syntax.

14) How can you check a function’s source code?

To inspect a function’s source code, the function must be invoked without parentheses.

15) What is the syntax command telling you whether or not you’re on the master server? And how many masters is Mongo permitting?

Db.isMaster) (command syntax will inform you whether or not you are on the master server. MongoDB only permits one master server, while CouchDB permits various masters.

16) Refer to the command syntax that Mongo uses the connection to view?

The syntax of the command used to display mongo is db. adminCommand(“connPoolStats.)

17) Explain what are Mongo indexes?

In MongoDB, indexes are unique structures that store a tiny part of the information set in a simple manner to traverse. The index stores the value of a particular field or set of fields, ordered by the field value specified in the index.

18) What is the fundamental syntax for using the Mongo index?

db. COLLECTION NAME.ensureIndex({ KEY:1}) is the fundamental syntax to use in MongoDB. The key here is the name of the COLUMN (or KEY: VALUE pair) in the papers.

19) Explain what is Mongo’s GridFS?

GridFS is used to store and retrieve big files like pictures, video files, and audio files. It uses two files fs.files and fs.chunks by default to store the metadata of the file and the chunks.

20) What are MongoDB’s options?

A few decent options are Cassandra, CouchDB, Redis, Hbase.