NoSQL describes database designs that store and retrieve data using models other than the traditional relational table structure. This lesson introduces what NoSQL means, why it became popular, and the benefits and challenges that come with its use.
Relational databases organize data into tables of rows and columns, usually with a predefined schema. NoSQL databases use other data models, such as key–value pairs, documents, wide columns, or graphs. These models can be better suited to particular kinds of data and access patterns.
All flashcards
What is a NoSQL database?
A broad category of databases that use non-relational data models, such as key–value, document, wide-column, or graph structures.
What is polyglot persistence?
An approach in which an application combines multiple database types and uses each where its data model or capabilities are appropriate.
What is horizontal scaling?
Increasing capacity by distributing data or work across multiple machines, rather than relying only on a larger single machine.
What is a stale read?
A read that returns an older value because an update has not yet reached all relevant nodes in an eventually consistent system.
What is write-ahead logging used for?
It records changes before they are applied, which can help a database recover and reduce the risk of losing writes.
Quiz questions
How can documents in a document database collection differ from one another?Answer: They can contain different sets or sequences of fields.
What is central to how a graph database represents and queries information?Answer: Relationships represented as connections among elements.
What can happen during eventual consistency?Answer: A read made shortly after an update may briefly return an older value, called a stale read.
Why might an organization be reluctant to adopt NoSQL?Answer: It may already have invested in relational databases, tools, and staff expertise.
How did the 1998 use of the term NoSQL differ from its modern broad usage?Answer: Strozzi used it for a relational database without a standard SQL interface, while modern NoSQL generally refers to non-relational databases.
Based on the Wikipedia article NoSQL, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.