MongoDB is a document-oriented NoSQL database for storing large amounts of data. MongoDB uses lists and records instead of tables and rows, as in conventional relational databases. . In this article, we will discuss, MongoDB interview questions, and MongoDB interview questions and answers.

MongoDB interview questions

Here are some Important MongoDB interview questions and answers:

  • What exactly is MongoDB?

MongoDB is a database that focuses on records. MongoDB is an efficient, scalable, and data-flexible database that delivers high performance when dealing with large volumes of data and can also be used as a NoSQL database. The data is stored in BSON format in MongoDB.

  • What distinguishes MongoDB from other databases?

The following are MongoDB’s main features:

  • Exceptional results
  • Scaling is done automatically.
  • Language for complex queries
  • Availability is high.
  • How does MongoDB handle transactions and locking?

MongoDB does not use traditional locking with reduction because it is designed to be light, quick, and understandable. It can be thought of as a counterpart to MySQL’s MyISAM auto entrust sculpt. Performance is improved with the simplest business maintenance, particularly in a framework with multiple servers.

  • When and how does data become multi-slice, and to what extent?

MongoDB scrap is a list of MongoDB scrap. As a result, a lump or mass is kept as an album of all substances. There would be more than a few slice data achievement options only if there is an extra time slot, so when there is more than one lump, data is expanded to a lot of slices and can be extended to 64 MB.

  • What’s the difference between MongoDB and MySQL, and how do you tell the two apart?

Even though MongoDB and MySQL are both free and open-source databases, they vary significantly in terms of data representation, relationship, transaction, data querying, schema design and definition, performance speed, normalization, and other factors. Comparing MySQL and MongoDB is comparable to comparing relational and non-relational databases.

  • Explanation of the term “oplog.”

The operational log (oplog) is a form of a capped set that keeps track of all operations that change the data in your databases. It first performs database operations on the primary, then logs the results in the primary’s oplog. After that, asynchronously, the secondary members copy and execute these operations.

  • In MongoDB, how does journaling work?

While journaling is in progress, write operations are saved in memory. Since journal writes are routine, the on-disk journal files are extremely dependable. MongoDB creates a journal subdirectory within the DB path.

  • In MongoDB, what are indexes?

Indexes are used in MongoDB to speed up query execution. Without indexes, MongoDB must conduct a collection search, which involves scanning every document in a collection to find those that fit the query argument. If a query has an acceptable index, MongoDB may use it to restrict the number of documents it must inspect.

  • Why isn’t the 32-bit version of MongoDB preferred?

Since MongoDB uses memory-mapped files, the total storage size of the server is 2 GB when using a 32-bit construct. However, if you use a 64-bit version of MongoDB, you can store almost as much data as you want. As a result, 64-bit is preferable to 32-bit.

  • Explain replication and when it’s necessary to use it.

Replication is the method of synchronizing data through different servers to ensure the data is never lost. With several copies of data on other storage servers, it offers consistency and improves data availability. It can be used for a variety of purposes, including data protection, high data availability, disaster recovery, and maintenance with no downtime.

  • When and to what degree does multi-slice data get extended?

The MongoDB scrap is based on a collection of items. As a consequence, everything is kept in a lump or mass. There will be more than a few slice data achievement options if there is an extra time slot, so if there is more than one lump, data can be expanded to several slices and can also be extended to 64 MB.

  • What exactly is a NoSQL database?

The acronym NoSQL stands for “Not Just SQL.” NoSQL is a category of Database Management System (DBMS) that does maintain all the rules of traditional RDBMS systems. Some of the well-known NoSQL database systems are – Cassandra, BigTable, DynamoDB, MongoDB, etc.

  • What are the different types of documents?

The text is the beating heart of MongoDB. In layman’s terms, the paper is a list of keys and their values. It’s similar to the table rows in relational databases. It always maintains a dynamic scheme, so no predefined structure or fields are needed.

  • Define the storage engine in MongoDB with an example?

A storage engine is a component of the database that manages data storage on the disc. For example, if two storage engines are available, one will support read-intensive workloads while the other provides higher throughput for writing operations.

  • What is the role of the profiler in MongoDB?

The MongoDB database profiler displays the performance characteristics of each database operation. Using the profiler, you will classify queries that are slower than they should be.

  • Define the term “auditing.”

Administrators may use auditing to make sure that the security measures in place are in charge of the system’s operation.

  • MongoDB is a type of database.

MongoDB is a document-oriented database management system. It’s similar to MySQL, except instead of RDBMS tables, the data model is made up of JSON-like items. MongoDB, for example, does not allow joins or transactions. MongoDB has built-in horizontal scaling through automated range-based partitioning and master–slave replication with automated failover.

  • MongoDB is written in which language?

MongoDB is written in the C programming language. Drivers and client libraries, on the other hand, are usually written in their own languages. Some drivers, however, use C extensions to boost performance.

  • Is it possible to delete files in the moveChunk directory that are no longer needed?

Yes, since these files are generated as backups during normal shard balancing operations, they can be removed once the operations are completed. This is a manual cleaning process that is required to make space.

  • Is it important to call “getLastError” for a write to be persistent?

No, calling “getLastError” is not needed (Safe Mode). The server acts as though it has been named in this case. The “getLastError” function simply confirms that a write operation has been successfully committed. You’ll like proof here, but the writer’s protection and reliability are unrelated.


MongoDB is a document database that allows you to store data in JSON documents. This MongoDB Interview Questions and Answers blog is dedicated to giving you a better understanding of the types of MongoDB interview questions you might face. Recruiters usually begin by asking simple questions and progressively raise the difficulty level of the questions as the interview progresses. As a result, this MongoDB interview questions blog has been created to meet the needs of the industry.

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