This content is part of the Essential Guide: Guide to NoSQL databases: How they can help users meet big data needs

Essential Guide

Browse Sections

The buzz: What are NoSQL databases?

Much fuss is made about these newcomers, but questions still arise. Mainly, they don't run on SQL, but that's not the full story.

NoSQL databases are most easily defined by what they aren't -- reliant on Structured Query Language, or SQL. But what are NoSQL databases? Trading relational models for a distributed, schema-less data structure, NoSQL databases are highly scalable and have gained popularity riding a wave of massively parallel Web applications. There are many categories of NoSQL designs -- key value, graph, document-oriented -- and well-known technologies include BigTable, HBase, Cassandra, Couchbase, MongoDB and SimpleDB.

The buzz

Still want to know -- what are NoSQL databases?

NoSQL database technology makes it to ThoughtWorks

MPP hardware, NoSQL databases: New DBMS options

Can Oracle peddle NoSQL databases?

Developers looking to build big Web applications needed to add more and more processing nodes to keep up with almost boundless demand for computing power. Relational databases came up short, so software engineers at Google, Amazon, Facebook and Yahoo devised non-SQL solutions -- laying the groundwork for big data analytics and expanded cloud computing services. Since 2009, a cavalry charge of NoSQL software startups entered the void with commercial products.

The reality

NoSQL is also known as "not only SQL," because some NoSQL databases do support SQL elements. But most don’t share key traits of relational databases like atomicity and consistency, so though NoSQL may help keep the auction chant going on eBay, it might break any bank using it for transaction processing. And with a ready pool of skilled developers, the incumbent relational database will hold on in most business applications.

A short history of NoSQL's origins

Dig Deeper on Database management system (DBMS) software and technology