Redis as Cache: How It Works and Why You Should Use It

Optimizing a Content Management System (CMS) in the context of web applications is a frequent occurrence today. Whether you're running your own WooCommerce site, Shopify store, or WordPress blog, having a website that runs efficiently is paramount for your success. Over time, WordPress sites have increased, which isn't surprising since they are customizable and have thousands of themes and plugins.

According to W3Techs, over 65% of CMS websites use WordPress, with Shopify coming in second. This fact means that you've most likely visited a site that's using WordPress. Although these websites are highly customizable, such customizations can lead to slow performance. This is exactly where implementing Redis as cache can enhance your overall webpage loading speeds.

If you've visited a WordPress blog recently, you may have noticed how the site functioned while trying to enjoy its content. Was it sluggish and slow to load? Did the front end have trouble loading the content for you? If that was the case, there's a chance the dynamic content isn't being cached properly.

If your site suffers from a caching issue, visitors may stop coming to your site, or you may be penalized by Google in the SERPs (Search Engine Results Pages) in terms of rankings. In short, you need to speed up your website to get better performance. So, let's learn how caching works and why you should use a Redis as cache scheme.

What Does Caching Mean?

If you have a computer, then you've used caching in some form or another. When your website displays content to site visitors, it's constantly querying the data from your web server. This process is always happening, and it takes time for your web server to verify that the information is correct, keep things secure, and provide the content to the visitor.

When speaking of "caching," it simply means that it's a virtual component in computing that will store data temporarily so it can be accessed again. As a WordPress user, you should know of the two kinds of caching systems:

• Client-Side Cache — Uses your computer to store the data, usually in the browser caching system.
• Server-Side Cache — Uses the server caching system to store data for later use.

There is quite a bit more to caching, but this keeps things simple. The default caching system for WordPress uses a non-persistent, single-object cache known as WP_Object_Cache, which is designed to last only for a single request.

1. Why Does Your Server Store Data for Later Use?

Have you ever been troubleshooting your computer issues online and have been told to "Clear the cache?" As mentioned, caching is just a temporary storage solution that keeps the information your application needs on hand instead of requiring multiple queries to the database. While this data is stored temporarily, sometimes the cache isn't cleared properly.

Over time, a caching system doesn't work as it should or doesn't get cleared of the temporary information from a server you accessed. If this occurs, there are usually issues with the website's page loading or applications not working correctly. This scenario is often true for more extensive databases or online stores with more content.

Larger databases monopolize resources and slow everything down, causing bottlenecks and drastically reducing performance. When managed properly, a cache improves your performance and speeds up your website.

2. What is a Data Structure Server?

In programming, a data structure is a specialized formatting template for organizing, retrieving, and storing your data; it contains data values and relationships between the data itself. All data structures are designed for a specific purpose, primarily for accessing and working with them in specific ways. Data structures are stored in a data structure store or server to access when needed or for later use.

While the data structures in the server may not mean as much on their own, they are building blocks for many applications. The data is molded into a specific type based on the applications that need it. If you don't use the proper data structure, it could cause sluggish runtimes and even unresponsive code.

What is Redis?

Data structures help manage the information in your database and provide access from a data structure store. If you started up a website and are running into issues with slow-loading pages and no improvements in speed, then Redis may be the answer. Remote Dictionary Server (Redis) is an in-memory data store that offers superior performance over traditional caching systems.

Redis, while capable of functioning as a NoSQL database, is primarily designed as an in-memory data store for high-performance, low-latency data access. Like any other cache, it can store and retrieve data quickly to improve the performance of your website. Redis (as cache) is versatile and supports many data structures like hashes, lists, sorted sets, and strings.

Still, why should you use Redis as cache instead of WordPress' default cache?

Why Should You Use Redis as Cache for Your Frequently Accessed Data

Redis as cache is used by countless organizations to improve the function of their website and other applications. There are specific reasons why a Redis-based caching solution is preferred over other options. Here are a few of them.

1. You Can Protect and Store Frequently Accessed Data Structures

Many organizations use Redis cache because it's fast and reliable. While Redis does support authentication, it does not natively support data encryption at rest or in transit. Extra measures, such as using a Secure Socket Layer (SSL) proxy or third-party solutions, are needed to secure data. It also supports most programming languages. While Redis offers data persistence and replication options, these are not enabled by default and need to be configured according to your application's needs.

2. You Can Decrease Data Access Latency

WordPress uses many object types that need to be accessed to display its content. This facet of WordPress means your browser has to consistently query the database. By doing this, your site is subject to performance bottlenecks. A Redis cache removes this obstacle by storing frequently accessed in-memory data so that it's available on demand.

By storing the information in memory, your browser doesn't have to query the database repeatedly. Therefore, your site's performance will be significantly improved. Redis also has a built-in feature that allows it to replicate the stored data so it's always ready. Now that you know why the Redis as cache implementation is preferred over other options, let's dive deeper into how it works.

How Does Redis Cache Work?

As discussed, Redis cache is an ideal solution for the backend side of your website, but how does it improve operations? Redis cache functions under the principles of a dictionary in the programming world. In programming, a dictionary is a critical data structure with two joined variables — a value and a key.

Typically, a key is used to authenticate or access protected data, and it works much the same way for Redis cache. Using the key, Redis cache will access the data it needs and assign that query a key. The value is the data that the Redis cache accessed, and because of this relationship between a key and a value, the Redis as cache system uses the key to get the data any time it's needed.

Data can be retrieved as many times as the user needs it. The amount of time the data stays in memory depends on the cache setup, which can be configured to automatically evict older data using various strategies, making it suitable for use cases where data freshness is essential.

Redis as Cache — Benefits

Redis is an open-source data store that improves the performance of many applications. Because it can deliver millions of requests per second, it's preferred by many organizations. However, Redis cache isn't just fast. It also offers other incentives to those who use it. Since June 2015, Redis development has been sponsored by Redis Labs, whose website provides many insights into using Redis-as-cache architecture for your website or application.

1. It's Simple and Versatile

Redis is a simplistic system that can accomplish complex functions with fewer lines of code. It supports common programming languages, such as Java, Python, JavaScript, PHP, and Node.js. With its versatility, it can store and use data with simple commands instead of complex query languages.

2. It's Open Source

Redis is a free and open-source solution that was created by Salvatore Sanfilippo to enhance the scalability of his software project while improving performance. Redis can be used as a cache, database, message broker, and queue because of its response times. It should be clear now why Redis is so sought after as a website caching system, but it's useful for more than that.

What is Redis as Cache Used For?

Among its many uses and use cases, Redis is a solid performance-enhancing option for object caching for CMSs including:

• WordPress
  • Object Cache Pro is one of a number of plugins that integrate with WordPress and Redis, and it is considered one of the best Redis integration plugins for WordPress.
  • The other options are the Redis Object Cache (free), WP Redis (free), W3 Total Cache, and Hummingbird (which uses Redis Object Cache code) plugins.
• Magento 2
• Drupal
• ExpressionEngine
  

Redis as cache enables low-latency and high-memory availability for many applications, meaning that it's not only helpful for caching WordPress and other CMS-based websites. Other popular Redis as cache uses throughout the technology landscape are:

• Gaming — Any experienced gaming developer should be aware of Redis' use cases for gaming. Developers will typically use Redis for real-time leaderboards.
• Chat Rooms — Since Redis can support many data structures, namely sorted sets, hashes, and lists, it works well for high-performing chat rooms. These chat rooms usually have social media feeds and real-time comments.
• Machine Learning — Many modern data applications need machine learning to function. Machine learning helps these applications process large amounts of data to automate the decision-making process. While Redis can contribute to a machine learning architecture by providing low-latency access to model inferences, particularly with the RedisAI module, it is not inherently a solution for machine learning itself.

A Redis system has many uses, but it's common to see them used for WordPress websites. If your website is running the default object caching system, it's recommended that you enable Redis as cache instead, and there are several plugin options to choose from as discussed in the previous sections.

Conclusion

Redis cache is a high-performing, in-memory data structure that can greatly improve your website's functionality. However, it isn't a perfect solution. Indeed, it has its limitations, but most WordPress sites don't have the data load to render it obsolete. Despite its few limitations, Redis cache is still useful today and can reduce the burden on slower server layers.

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