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What Is a NoSQL Database?

A NoSQL database is a distributed, non-relational database designed for large-scale data storage and for massively-parallel, high-performance data processing across a large number of commodity systems. Unlike the traditional relational database approach, NoSQL gives you a way to work with data that is closer to the application. It is a modern data storage paradigm that provides data persistence for environments where high performance is a primary requirement. Within a NoSQL database, data is stored in such a way that both writing and reading are fast, even under heavy load.

As your business grows, so will your database. NoSQL databases are typically distributed systems in which several machines work together in clusters to provide data and each piece of data is replicated over those machines to deliver redundancy and high availability. The ability to store huge amounts of data in a distributed manner makes NoSQL databases faster to develop and deploy. NoSQL databases are built for specific data models and have flexible schemas that allow programmers to create and manage modern applications.

Example of SQL tabular structure vs NoSQL multimodel data formats

Why are NoSQL databases so popular?

NoSQL databases have become increasingly popular due to their flexible data model, high performance, high scalability, and ease of access. These databases are purpose-built solutions designed to provide highly fault-tolerant data management and the ability to continue operating even after multiple hardware and system failures. These systems originated to provide high throughput, fault-tolerant, horizontally scalable, simple data storage and retrieval with a bare minimum of additional functionality. 

NoSQL databases are designed to scale out and leverage cloud computing. They can support a wide set of use cases, including exploratory and predictive analytics in real time. They are meant to scale horizontally, and are designed to handle hundreds of millions and even billions of users doing updates and reads.

Why do developers love NoSQL?

Developers have been quick to adopt NoSQL databases due to their flexible schema, efficient processing, and storage of unstructured and semi-structured data—plus their ability to support high-performance queries in a scaled out environment. Here are some of the key reasons why developers love NoSQL:

  1. Flexible data modeling

NoSQL offers the ability to implement flexible and fluid data models for developers. Developers choose NoSQL databases when they require semi-structured or unstructured data with flexible schema. A flexible data model doesn’t restrict developers to a defined schema. The dynamic schema allows developers to make schema changes to a structure without taking the structure offline. Application developers can leverage the data types and query options that are the most natural fit to the specific application use case rather than those that fit the database schema. The result is a simpler interaction between the application and the database and faster, more agile development.

2. Developer friendliness

NoSQL allows developers to build faster and more responsive applications that can take advantage of real-time data. Most existing NoSQL databases provide client interfaces and drivers for all common developer languages, including C, C++, Java, Python, Go, Rust, and many others.

3. High availability and built-in replication

NoSQL databases are generally designed to ensure high availability and avoid the complexity that comes with a typical RDBMS architecture that relies on primary and secondary nodes.

By automatically replicating data across multiple servers, data centers, or cloud resources, distributed NoSQL databases can minimize latency and ensure a consistent application experience wherever users are located.

4. Scalability and performance

A NoSQL database is not only used for its performance and high availability but also for its robust query language and simple scalability. A NoSQL distributed database is designed with a scale-out architecture and no single point of failure, providing compelling operational advantages. NoSQL database partitions and distributes data to multiple database instances with no shared resources. This means that by simply adding commodity resources, organizations can increase performance with NoSQL databases. This enables organisations  to continue to deliver reliably fast user experiences with a predictable return on investment for adding resources—again, without the overhead associated with manual sharding.

5. Easier operability

A NoSQL database is simple but robust. These databases are easier to install and configure. Both command line interfaces and GUI tools offered by most NoSQL database vendors allow developers to browse and explore databases and intuitively interact with data.

How is a NoSQL (non-relational) database different from a SQL database?

Feature NoSQL SQL
Performance NoSQL is much faster than relational databases in terms of read and write speed, especially in key-value storage systems. That means less waiting time in use cases such as online transactions.
Relational databases require an intensive amount of configuration (queries, optimisation, and indexing) to reach the performance of NoSQL. They are mostly dependent upon the disk subsystem for read and write speed.
Schema and data model Instead of a declarative query language, NoSQL databases have dynamic schema for unstructured data. NoSQL databases are either document-based, key-value pairs, graph databases, or wide-column stores. Relational database management systems (RDBMS) use Structured Query Language (SQL) and have a predefined schema. They are table-based and composed of rows and columns.
Ease of scalability Most existing NoSQL databases scale horizontally, meaning you can add more servers to power your growing database. You handle increasing traffic by sharding, or adding more servers in your NoSQL database. Scaling out with SQL databases is possible, but requires extensive effort (partitioning, sharding, clustering, etc.) and cost. They are mostly vertically scalable, which means you can handle increased loads on a single server by increasing processing power, memory, or fast storage.
Consistency Eventual consistency is the most common consistency level used in NoSQL. That said, some NoSQL databases support strong consistency. Strong consistency is the most common consistency level used in SQL databases.  
ACID vs CAP NoSQL offers high availability and auto-replication (automatically communicating with another instance when one goes down), and follows the CAP theorem. Emphasizes ACID (atomicity, consistency, isolation, durability) properties 

When to use a NoSQL database

  • When you are rapidly developing an application that requires frequent database schema changes and the traditional RDBMS model is too restrictive.
  • When you want to get rid of complex queries and complex inner joins are affecting application performance
  • When your data needs scale up, scale out, and scale down
  • When ACID support is not really needed
  • When rapid development and frequent updates are common
  • When you want to store large data volumes

Don’t miss: 5 Steps for Selecting a High-Performance NoSQL Database

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Next section  ►  Key-Value Databases