When it comes to choosing a database for your project you are often left with two options i.e. SQL vs NoSQL databases. Newbie developers most often learn one database technology and try to use it in all the projects. However, this is a bad practice.
Both databases are viable options but some applications are better served by using a particular kind of database.
This article will learn the differences between these two database technologies, which will help you decide on the right database for your application.
What are SQL databases?
SQL databases are also known as Relational Databases. They use SQL language. SQL (structured query language) is the standard language used for querying and manipulating data in a relational database.
Relational databases refer to the relational model of data management. They have a rigid schema. They store data in the form of tables. The tables contain a fixed number of columns which are the attributes of the data. The data is stored in various rows. A row of data is known as a tuple. Every tuple contains either a genuine value or null value for every column. They also support the concept of keys and joins between tables.
Relational databases are ACID compliant. ACID stands for atomicity, consistency, isolation and durability. It is a set of properties that guarantee data validity despite errors, power failures and other mishappenings.
Relational databases are vertically scalable. It means they are scaled up by adding resources to the database server to make it more powerful. Relational data is difficult to spread across multiple servers.
Some examples of relational databases are - MySQL, PostgreSQL, Microsoft SQL Server, and MariaDB.
NoSQL databases as the name suggest don't use SQL. They don't require a fixed schema, don't support joins and are easier to scale. They don't store data in tables, instead, they use key-value pairs, documents, or graphs to store data.
NoSQL databases don't have a fixed schema, That's why they are suited for cases when the data collected is not consistent e.g. IoT data. They are best suited for distributed data. Therefore they are used for building real-time applications, big-data analytics etc.
Most of the NoSQL databases do not follow ACID properties. MongoDB is the most popular NoSQL database which is also ACID compliant. NoSQL databases follow the BASE property. It stands for Basically Available, Soft State and Eventually Consistent.
E.g. MongoDB, Dgraph, Couchbase, Redis, and Amazon DynamoDB.
When to use SQL Databases.
- Relational databases are best suited if you are building apps where ACID support is needed. E.g. financial apps, e-commerce.
- If the data is related to each other (e.g. social media) relational databases are the best option.
- If the data is structured you should use relational databases.
When to use NoSQL databases?
- When ACID support is not needed.
- When the data has a flexible schema.
- When storing data in a distributed manner.
- When constraints are not needed.