What is MongoDB ?

MongoDB is a NoSQL database which is document-oriented and is used for high volume data storage. MongoDB makes use of collections and documents, instead of using tables and rows as in the relational databases. Documents contain key-value pairs which are considered as the basic unit of data in MongoDB. Collections consists of set of documents and function which is the equivalent of relational database tables.

  • In MongoDB, each of the database consists of collections which in turn comprises of documents. Each document might be different with a varying number of fields. The size and content of each document can be different from each other.
  • The document structure is more specific to how developers construct their classes and objects in their respective programming languages. Developers will often say that their classes have a clear structure with the different key-value pairs.
  • The documents in MongoDB does not need to have a schema defined beforehand. Instead, the fields can be created instantly.
  • With MongoDB, it is possible to represent hierarchical relationships, to store arrays, and other more complex structures more easily.

What is MySQL ?

MySQL is an open-source relational database management system developed by Oracle which is free to use and very popular.

  • MySQL stores data using tables and rows, enforces referential integrity and uses structured query language i.e., SQL for accessing the data.
  • Users must construct an SQL query that joins multiple tables together to create the view on the data in order to retrieve the required data.
  • Database schemas and data models need to be defined ahead of time, and data must match this schema to be stored in the database. Though, this rigid approach to storing data offers some degree of safety, but trades this for flexibility.
  • In case, a new type of data needs to be stored into the database, schema migration might occur which may become complex and expensive as the size of the database grows.

What are the key differences ?

The key differences between these two database systems are significant. Selecting a particular database, is really a question of approach rather than completely a technical decision.

MySQL is a relational database system which offers a familiar database environment for experienced IT professionals. On the contrary, MongoDB is considered to be a well-established, non-relational database system that offers improved flexibility and horizontal scalability, but at the cost of some safety features of relational databases, such as referential integrity.

In the following section, let us look at some of the key differences between these two systems :

1. User-Friendliness

Currently, MongoDB is an attractive option to developers as its data storage mechanism is simple and immediately understandable to anybody with programming experience. It stores data in collections with no predefined schema. This flexible approach to storing data makes it particularly suitable for the majority of developers who just want to use a database to support the development of their applications.

On the contrary, MySQL is a suitable option for developers who have extensive experience using traditional SQL scripting, designing solutions for relational databases, or those who are modifying or updating existing applications with a relational system. Relational databases may also be a better choice for applications that require very complex but rigid data structures and database schemas across a large number of tables.

2. Performance

Comparing the performance of two completely different database systems is difficult as both of the systems approach the task for data storage and retrieval in completely unique manner. Though it is possible to directly compare two SQL databases with a set of standard SQL benchmarks but achieving the same across non-relational and relational databases is much more difficult.

We can say that, MySQL is optimized for high performance joins across multiple tables which have been appropriately indexed. In MongoDB, joins are supported with the "$lookup" operation, but they are less needed due to the way MongoDB documents tend to be used. They follow a hierarchical data model and keep most of the data in one document, thereby eliminating the need for joins across multiple documents.

3. Security

MongoDB leverages the popular role-based access control model with a flexible set of permissions. Users are assigned to a role, and that role grants them specific permissions over data sets and database operations. All communication is encrypted with TLS, and it’s possible to write encrypted documents to MongoDB data collections using a master key which is never available to MongoDB, achieving encryption of data at rest.

MySQL supports the same encryption features as MongoDB; its authentication model is also similar. Users can be granted roles but also privileges, giving them permissions over particular database operations and against particular data sets.

4. Scalability

Another special benefit of the MongoDB design is that the database is extremely easy to scale. Configuring a sharded cluster allows a portion of the database known as a shard, to also be configured as a replica set. In a sharded cluster, data is distributed across many servers. This highly flexible approach allows MongoDB to horizontally scale both read and write performance to cater to applications of any scale.

With a MySQL database system, options for scalability are much more limited. Typically, you have two choices: vertical scalability, or adding read replicas. Scaling vertically involves adding more resources to the existing database server, but this has an inherent upper limit.

5. Flexibility

MongoDB is more flexible as compared to MySQL. The schema-less design of MongoDB documents makes it very easy for building and enhancing applications over time, without needing to run complex and expensive schema migration processes as we would need with a relational database.

In addition, MongoDB also offers MongoDB Atlas which is a managed cloud solution and free to use for exploratory purposes. But, on the other hand, for a MySQL managed cloud version, we would need to have an account with one of the major public cloud providers and fall within their free tier terms in order to be free.

Summary

  • In this article, we have explored the two most popular database systems i.e., MongoDB and MySQL along with their unique features.
  • We also discussed their various key differences regarding scalability, performance, flexibility, security and user-friendliness for each system.
  • Therefore, we also understood which of the two database systems should be used in particular situations according to the mentioned factors.