What is Redis and Why You Should Use It

If you’re new to Redis, you may be wondering what exactly it is and who should use it. So, we spent some time putting together this overview that will give new users a better idea of what it is and how it works.

After reading this post, if you find yourself still needing assistance, I encourage you to check out our Redis support options. We have decades of experience with Redis and can get you on track rapidly.

What is Redis?

Redis (which stands for REmote DIctionary Server) is an open source, in-memory, NoSQL key/value store that is primarily used as an application cache or quick-response database. It provides unrivaled speed, reliability, and performance since it saves data in memory rather than on a disk or solid-state drive (SSD).

When an app uses external data sources, the latency and throughput of such sources might be a performance barrier, especially as traffic grows and the app scales. In these instances, one method to increase performance is to store and manipulate data in memory, which is physically closer to the application.

This is why Redis was created: It keeps all data in memory for the fastest possible performance when reading or writing data, and it has built-in replication capabilities that allow you to physically place data closer to the user for the lowest possible latency.

Other Redis characteristics worth noting include support for multiple data structures, built-in Lua scripting, multiple levels of on-disk persistence, and high availability.

Why Use Redis?

Redis is perfect for amplification. Use it to store website sessions across multiple servers, keep a user’s login even if he connects to a different server of the same website.

For example, Facebook’s load balancer tries to keep the user assigned to the same server on each access, but if that isn’t possible, the user won’t lose his session because the session store is shared across the different instances.

Aside from session storage, Redis has other uses. You can use it to send messages to every server that listens to a channel using Publisher/Subscriber technologies.

Implementing a message or job queue, where a master posts jobs and workers take jobs from the queue to process them, Redis stores random data that has to be accessed quickly by numerous servers. Because Redis supports a wide range of data types and even value structures, there are numerous use cases.


  • Fast Performance
  • Simplicity
  • Open Source
  • A wide range of Data Structures
  • Capable of withstanding failures

Fast Performance

Redis has become popular for a reason, it’s incredibly fast. In fact, it’s roughly 10 – 30% faster when the data set fits within working memory of a single machine. In order to maintain data, you can attach all commands to a log or just save it intermittently.


Redis allows for users to write complicated code quicker and more easily. Redis keys are strings, which can also be used as values, this maps strings to other strings.

It utilizes a hash data structure that allows you to move data with just one line of code, whereas other data stores would require multiple lines of code.

Open Source

Redis is open source and utilizes a BSD license, similar to FreeBSD. At A-Team systems, we’re passionate about open source projects and the freedom that provides developers and the internet as a whole. Therefore, we’re proud supporters of open source projects.

A Wide-range of Data Structures

Redis features many different data structures, including:

  • Hashes
  • Strings
  • Lists
  • Sets
  • Geospatial
  • Bitmaps
  • Hyperloglog

Capable of Withstanding Failures

Redis can utilize efficient replication, which allows the cache service to be functional, even when slave nodes are down. This gives the nodes time to overcome the failure and start functioning again.


  • In-memory storage
  • No query language
  • Limited access rights
  • Unique instances are not scalable

In-memory storage

With in-memory storage, all your data needs to reside in memory. This means that you’re limited by the amount of memory that you have. Compare this to Relational Database Management Systems that typically store some data on disks, and some of it in memory. Therefore, you can store more data than you have memory.

No query language

Because Redis is a data structure server, there is no query language. You can’t submit one-off queries, like you can with a SQL database. Developers will need to facilitate data access paths.

Limited access rights

Redis only has three levels of access rights at the instance level. “Full Access,” “Not Dangerous,” and “Read Only.” Other systems allow for full configuration of per-object access control lists.

Unique instances are not scalable

Several Redis instances are required for multi-core machines. In single-threaded mode, an instance can only run on one CPU core. Therefore, additional configuration is required.

Common Use Cases for Redis


Redis is an excellent solution for implementing a highly available in-memory cache to reduce data access latency, boost throughput, and relieve pressure on your relational or NoSQL database and application.

Redis can provide frequently requested items in milliseconds or less, and it allows you to scale for higher loads without having to expand the more expensive backend. Redis caching is commonly used for database query results caching, persistent session caching, web page caching, and caching of frequently used objects including images, files, and metadata.

Real-time analytics

Redis can be used as an in-memory data storage with streaming solutions like Apache Kafka and Amazon Kinesis to process, and analyze real-time data with sub-millisecond latency.

For real-time analytics use cases like social media analytics, ad targeting, personalization, and IoT, Redis is an excellent solution.

Machine Learning

Machine learning is required in modern data-driven applications to efficiently process a large volume, diversity, and velocity of data and automate decision-making. The ability to process live data and make decisions in tens of milliseconds is critical for use cases such as fraud detection in gaming and financial services, real-time bidding in ad-tech, and matchmaking in dating and ride-sharing. Redis is a fast in-memory data store that allows you to quickly build, train, and deploy machine learning models.


To manage real-time geospatial data at scale and speed, Redis provides purpose-built in-memory data structures and operators. GEOADD, GEODIST, GEORADIUS, and GEORADIUSBYMEMBER are commands that store, process, and analyze geospatial data in real time, making geospatial data easy and fast with Redis.

Redis can be used to offer location-based features to your applications, such as drive time, drive distance, and points of interest.

Rich media streaming

Redis is a fast, in-memory data store that can be used to power live streaming use cases. Redis can store metadata about users’ profiles and viewing histories, as well as authentication information/tokens for millions of users and manifest files, allowing CDNs to stream films to millions of mobile and desktop users simultaneously.

Session store

Redis is a popular choice among application developers for storing and managing session data for internet-scale applications since it is an in-memory data store with excellent availability and persistence.

Redis offers the sub-millisecond latency, scalability, and resiliency required to manage session data such user profiles, credentials, session state, and user-specific personalization.

Gaming leaderboards

When it comes to creating real-time leaderboards, Redis is a popular choice among game developers. Simply use the Redis Sorted Set data structure, which ensures that elements are unique while keeping the list sorted user scores.

It’s as simple as updating a user’s score each time it changes to create a real-time ranked list. Sorted Sets can also be used to handle time series data when timestamps are used as the score.

Messaging, Chat and Queues

Redis supports Pub/Sub and a range of data structures such as lists, sorted sets, and hashes, as well as pattern matching. Redis can now handle high-performance chat rooms, real-time comment streams, social media feeds, and server-to-server communication.

A lightweight queue can be easily implemented using the Redis List data structure. Lists are excellent for a number of applications that require a reliable message broker or a circular list since they provide atomic operations as well as blocking.

Is Redis a Cache or Database?

Redis is both a cache and a database, depending upon the application. It began as a caching database, but over time, it became capable of being used as a primary database as well. There are applications that currently utilize Redis as a primary database, but overall, the most common usage is as a caching database.

Ready to Start Using Redis?

Hopefully you now have a better idea of what Redis is and when you should consider using it. It’s a dynamic cache/database with some impressive performance stats.

Remember, if you still have questions or need assistance working Redis into your system, we can help! Call us 24/7 at 828-376-0458 for open source experts that really understand Redis.


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