mongoDB Interview Questions and Answers

What do you understand by a test pyramid?

Testing Pyramid is a framework that can help both developers and QAs create high-quality software. It reduces the time required for developers to identify if a change they introduced breaks the code. It can also be helpful in building a more reliable test suite.

What do you understand by NoSQL databases? Is MongoDB a NoSQL database?

not only SQL

NoSQL, which stands for “not only SQL,” is an approach to database design that provides flexible schemas for the storage and retrieval of data beyond the traditional table structures found in relational databases.

NoSQL databases are databases that store data in a format other than relational tables. … NoSQL databases can store relationship data — they just store it differently than relational databases do.

Which are the different languages supported by MongoDB?

MongoDB uses the MongoDB Query Language (MQL), designed for easy use by developers.

What are the different types of NoSQL databases? Give some example

MongoDB, CouchDB, Cassandra, HBase

Is MongoDB better than other SQL databases? If yes then how?

MongoDB is almost 100 times faster than traditional database system like RDBMS, which is slower in comparison with the NoSQL databases. MongoDB supports deep query-ability i.e we can perform dynamic queries on documents using the document-based query language that’s nearly as powerful as SQL.

Why MongoDB is known as best NoSQL database?

Scalable and Reliable. MongoDB has grown from being just a JSON data store to become the most popular NoSQL database solution with efficient data manipulation and administration capabilities. … Database schema design, data modeling, backup and security are some of the common challenges faced by database administrators today.

Explain the structure of ObjectID in MongoDB?

An ObjectID is a 12-byte Field Of BSON type. The first 4 bytes representing the Unix Timestamp of the document. The next 3 bytes are the machine Id on which the MongoDB server is running. The next 2 bytes are of process id. The last Field is 3 bytes used for increment the objectid.

What are Indexes in MongoDB?

An index in MongoDB is a special data structure that holds the data of few fields of documents on which the index is created. Indexes improve the speed of search operations in the database.

Indexes are special data structures, that store a small portion of the data set in an easy-to-traverse form.

What is a Namespace in MongoDB?

MongoDB stores BSON (Binary Interchange and Structure Object Notation) objects in the collection. The combination of the collection name and database name is called a namespace.

Do the MongoDB databases have schema?

Yes, Data in MongoDB has a flexible schema.

Explain what a callback function is and provide a simple example.

A callback function is a function passed into another function as an argument,

How to check if an object is an array or not? Provide some code?

You can use the JavaScript Array. isArray() method to check whether an object (or a variable) is an array or not. This method returns true if the value is an array; otherwise returns false .