🧰NoSQL

NEW

Also known as: Non-relational Database

A class of database systems that eschew the relational model to offer flexible schemas and horizontal scalability.

DESCRIPTION

NoSQL databases provide non-relational data models tailored for modern scalable applications. They include document, key-value, column-family, and graph stores, often prioritizing performance and availability over strict consistency. Many implement BASE properties and eventual consistency under the CAP theorem. NoSQL is popular for real-time analytics, caching, content management, and personalization. The approach enables schema flexibility and rapid iteration. However, transactional semantics and complex joins may be limited or implemented differently. Organizations often employ polyglot persistence, combining NoSQL with RDBMS or NewSQL systems.

ALTERNATIVE DEFINITIONS

Wikipedia

NoSQL is an approach to database design that enables the storage and querying of data outside the traditional structures found in relational databases.

Defines NoSQL as a design approach outside relational structures.

Source

Oracle

NoSQL databases are non-relational databases that store data in a format other than relational tables.

Vendor definition emphasizing non-relational data formats.

Source

RELATED TERMS

Document Store Key-Value Store Column-Family Store Graph Database CAP Theorem BASE Eventual Consistency Polyglot Persistence Schema-less

COMPETING TERMS

Relational Database NewSQL

RELATIONS

• Narrower: Amazon DynamoDB Apache HBase Azure Cosmos DB

KNOWLEDGE AREAS

Data Storage & Operations Data Engineering Data Architecture Cloud

TARGET AUDIENCE

Data Engineer Software Developer Data Architect Cloud Architect BI Specialist

EXTERNAL SOURCES

• Wikipedia - NoSQL
• Amazon Web Services - Overview of NoSQL databases
• Microsoft Learn - Choosing data stores including NoSQL
• Martin Fowler - Introductory NoSQL patterns

TOP QUESTIONS

What problems does NoSQL solve?

It addresses scalability, flexible schemas, and high availability for modern, data-intensive applications.

Category: Relevancy

Is NoSQL eventually consistent?

Many NoSQL systems favor eventual consistency, though some offer tunable or strong consistency options.

Category: Mechanism

Can NoSQL support transactions?

Some provide single-document or limited transactions; multi-document ACID varies by product.

Category: Differences

How does NoSQL model relationships?

Graph databases model edges explicitly, while document stores often embed or reference related data.

Category: Design

What is a common mistake with NoSQL?

Ignoring query patterns and designing collections that require excessive cross-document joins or scans.

Category: Mistakes

Is NoSQL suitable for analytics?

It can be, but many pair NoSQL with data warehouses or lakehouses for complex analytics.

Category: Opinion

How does NoSQL affect latency?

Denormalization and locality can reduce read latency; cross-partition queries may increase it.

Category: Performance

What is polyglot persistence with NoSQL?

Using multiple database types together, choosing the best fit per use case.

Category: Concepts

How do I choose a NoSQL model?

Map access patterns to data models: documents for aggregates, key-value for caching, column-family for wide tables, graphs for relationships.

Category: How-to