What Is MongoDB: The Best Guide to MongoDB for Beginners

MongoDB is a popularly used NoSQL (not only SQL) database. Surely, you would have heard about this several times, if you’re interested in this topic. This tutorial on What is MongoDB will give you a deep understanding of its working and applications. Here is the list of the topics covered:

  1. MongoDB Evolution
  2. What is MongoDB?
  3. Why MongoDB? 
  4. Salient Features of MongoDB
  5. Working of MongoDB
  6. MongoDB Applications
  7. Limitations of MongoDB
  8. Companies Using MongoDB

Now that you know what’s in store for you, continue reading the tutorial;

MongoDB Evolution

Structured Query Language (SQL) existed even before the World Wide Web. However, as websites' functionality grew, developers wanted to generate web pages using content that could change over time without redeploying the code. As a result, Not only SQL or NoSQL was developed. NoSQL has relaxed ACID (atomicity, consistency, isolation, durability) properties and guarantees better performance, scalability, flexibility, and reduced complexity. 

MongoDB was released on August 27th, 2009. Version 1 was basic, while version 2 introduced features like sharding, usable and special indices, geospatial features, memory, and concurrency improvements, among others. Version 3 came with an aggregation framework mainly as a supplement to the aging MapReduce framework.

What is MongoDB?


MongoDB is a document-oriented, no sequel (NoSQL) database. MongoDB helps avoid the concept of "rows" of conventional relational data models with the introduction of "documents." This provision offers developers to work with evolving data models too. 

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Since it is document-based, MongoDB allows embedded documents and arrays, it also represents a complex hierarchical relationship using a single record. MongoDB is schema-free, which means that the keys defined in the document are not fixed. As a result, massive data migrations are ruled out. 

Why MongoDB?

There are four major reasons why MongoDB is being deployed more often. They are:

1. Flexibility:

MongoDB uses documents that can contain sub-documents in complex hierarchies making it expressive and flexible. MongoDB can map objects from any programming language, ensuring easy implementation and maintenance.

2. Flexible Query Model:

The user can selectively index some parts of each document or a query based on regular expressions, ranges, or attribute values, and have as many properties per object as needed by the application layer.

3. Native Aggregation:

Native aggregation allows users to extract and transform data from the database. The data can either be loaded into a new format or exported to other data sources. 

4. Schema-less model:

Applications get the power and responsibility to interpret different properties found in a collection's documents. 

Salient Features of MongoDB


1. General-Purpose Database:

MongoDB can serve diverse sets of data and multiple purposes within a single application. 

2. Flexible Schema Design:

The document-oriented approach allows non-defined attributes to be modified on the fly. This is a key contrast between MongoDB and other relational databases. 

3. Load Balancing and Scalability:

It is built to scale, both vertically and horizontally. Using the technique of sharding, an architect can achieve both write and read scalability. Data balancing occurs automatically and transparently to the user by the shard balancer.

4. Aggregation Framework:

MongoDB offers an Extract, Transform, Load (ETL) framework which eliminates the need for complex data pipelines.

5. Native Replication:

Data gets replicated across a replica set without a complicated setup.

6. Security Features:

Authentication and authorization are taken into account. 

7. JSON:

JSON is widely used across for frontend and API communication. It only makes sense for the database to use the same protocol. 

8. MapReduce:

MongoDB offers a great tool, MapReduce to build data pipelines. 

Working of MongoDB


The entire database consists of collections. These collections hold multiple documents, and since MongoDB is schemaless, the documents in one collection need not be similar. All data is stored as BSON documents with the help of key-value pairs. At the backend, MongoDB converts JSON data into a binary format known as BSON. MongoDB also makes provision for nested data. This makes fetching data comparatively efficient.  

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MongoDB Applications

Several areas of technology use MongoDB as their Database Management System. 


Internet of Things (IoT), mobile applications, real-time analysis, personalization, catalog management, and content management, among others, readily deploy MongoDB. 

Limitations of MongoDB

  1. MongoDB uses high memory for data storage.
  2. The BSON document size cannot exceed 16MB.
  3. Naming restrictions for databases in Windows.

Companies Using MongoDB


Companies like Toyota, Cisco, Verizon, Barclays, and Google among others are readily deploying MongoDB as the DBMS. 

Next Steps 

We hope this tutorial on ‘What is MongoDB’ has helped you gain a better understanding of the DBMS. If you wish to make a career as a developer, then certification will come in handy. 

Simplilearn’s MongoDB Certification Training Course will help you master popular and essential topics like query, ingestion, sharding, data modeling, and data replication with MongoDB, along with the installation, update, and maintenance of the MongoDB environment. This course will also help you gain high-level proficiency in handling MongoDB configuration and backup methods, and the required monitoring and operational strategies. 

Have any questions for us regarding MongoDB? Place them in the comments section of this page, and our industry experts will get back to you soon!

About the Author


Simplilearn is one of the world’s leading providers of online training for Digital Marketing, Cloud Computing, Project Management, Data Science, IT, Software Development, and many other emerging technologies.

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