NoSQL Databases

So far, we have been working with structured data.

So what is structured data?

Data that can be organized neatly in a tabular format, where every row of the data follows a predefined, fixed schema definition, is structured data. The schema defines not only the number of columns but also the data type, constraints, etc., for the data that is saved in each cell. Every row of the table has to meet this schema's criteria. Thereby, the data in every row is consistent.

In very simple terms, since an RDBMS meets these criteria, if you are able to put your data into an RDBMS, then it is structured data. Every structured data storage can typically be queried using SQL (Structured Query Language).

What is unstructured data?

Any pile of data that cannot be schematized, normalized, and dropped into a database is unstructured data.

Some of the examples of unstructured data are:

  • Email messages
  • Blog posts, social media posts
  • Web pages
  • Video, images, and audio files, etc.

A few decades ago, we were only dealing with structured data because most businesses were run with structured data. Customer data, sales/revenue data, purchase order data—all of this data was highly organized and hence could easily be saved in a relational database. However, with the advent of social media platforms like YouTube, Facebook, Twitter, etc., which started generating piles of unstructured data that were nevertheless very valuable for businesses to analyze and interpret, there came a need for storing and processing these types of data.

A typical RDBMS was not optimal for storing and querying this type of data. New databases came into the market to address these needs, and NoSQL databases were born.

What is NoSQL?

NoSQL is an acronym for Not Only SQL.

Although the acronym says that, not every NoSQL database supports SQL, while some do support SQL to query unstructured data.

Most importantly, however, you can store data in these databases without defining a schema first.

Key Implementation Techniques
  • Key-Value Store
  • Document Store
  • Row/Column Store
  • In-Memory Data Structures

Reference: https://db-engines.com/en/ranking