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Glossary

What Is NoSQL

NoSQL databases store data in flexible formats rather than rigid tables. Learn what NoSQL is and when businesses use it instead of traditional databases.

Definition

NoSQL (which stands for "Not Only SQL") is a category of database systems that store data in formats other than the traditional rows-and-columns table structure. While relational databases like MySQL and PostgreSQL require you to define a rigid schema before storing data, NoSQL databases are more flexible. They come in several varieties: document databases store data as JSON-like documents, key-value stores pair simple keys with values, graph databases map relationships between entities, and column-family stores organise data by columns rather than rows.

Why It Matters

Not every type of data fits neatly into tables. User activity logs, product catalogues with varying attributes, social media feeds, and real-time analytics data are often easier to work with in a flexible format. NoSQL databases handle these use cases efficiently and can scale horizontally (spreading data across many servers) more easily than traditional relational databases. NoSQL is a complement to SQL databases, not a replacement. Most modern applications use both: a relational database for structured, transactional data and a NoSQL database for high-volume, flexible, or real-time data.

Example

An e-commerce platform sells products across dozens of categories, each with different attributes. Clothing has sizes and colours, electronics have specifications and compatibility details, and books have authors and page counts. Forcing all of these into a single relational table structure creates either empty columns or complex workarounds. Using a document-based NoSQL database, each product is stored as a self-contained document with only the attributes relevant to its category, making the data easier to manage and faster to query. Browse the full glossary for related definitions.

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