SQL databases versus NoSQL

One of the largest decisions to make when planning a new database deployment is whether to use a Structured Query Language (SQL) or Not only SQL (NoSQL) database. These two types of databases differ greatly and making the wrong choice can compromise the performance and the ability of your application to function.

First, let's discuss the key features of both database types before doing a deep comparison of both so that you can decide between them.

SQL databases

SQL databases are designed to excel in storing structured data. They can carry out complex querying and they commonly store the minimum data possible by reducing any duplication of the data in a table in a process known as normalization. Normalized data means that accessing it often requires complex joins of different tables.

Normalized data would look similar to this:

Figure 2.1 – RDBMS table structure

These tables only contain the specific columns...