1. Introduction to NoSQL

What is NoSQL?

• NoSQL stands for “Not Only SQL”, representing databases that provide flexible, non-tabular data storage.
• Unlike traditional relational databases (SQL), NoSQL databases can store structured, semi-structured, or unstructured data.
  Example:
  • Structured Data: A database of user profiles where every user has a name, email, and age.
  • Semi-structured Data: Log files where each entry has variable attributes (e.g., error messages with different parameters).
  • Unstructured Data: Storing images, videos, or text documents as data blobs in a database.

Characteristics of NoSQL Databases:

• Schema-less: Data can be stored without a predefined structure.

• Horizontally Scalable: Handle increasing amounts of data by adding more servers.

• High Performance:

  • Optimized for fast reads/writes, often at the expense of complex querying.
  • Explanation:
    • NoSQL databases prioritize speed and efficiency by storing data in a way that’s easy to retrieve but may not support intricate relationships or multi-step joins found in SQL. For example:
      • A social media feed retrieves user posts quickly without needing to calculate relationships in real-time.
      • However, performing a query like “find all users who commented on posts liked by another user” might be slower or more complex.

• Flexible Data Models: Instead of just storing data in strict tables, multiple data models (such as key-value, document, column-family, or graph models) are all supported

Comparing NoSQL to SQL