We love discussing complex topics in a digestible way in our Office Hours Q&A blog posts. For example, we recently spoke with Hans Skillrud from Termageddon about CIPA and the risks it poses to website owners.
Or how seemingly innocuous calendar spam can actually hide a scam. However, during our March 5, 2026, broadcast, a viewer asked a question so simple that it deserves a full blog explanation.
They wanted to know more about Redis and object cache. While these two technologies can get very complex (if we dig into how it actually works), their purpose and implementation are very simple to understand.
Our viewer’s question
As you saw in this blog’s introduction, we can get some rather layered questions from our audience. It’s always refreshing when we see a good old “What is?” one, though. So much so, it made Nathan, our knowledgeable host, smile with delight.
Here is the specific question:
Redis Object Cache - what is it, where do you use it? What does it do?
It’s a great question that Nathan covered during the livestream and that we’ll elaborate on a bit further in this blog. There are two terms in that question (Redis and Object Cache), so let’s define them separately first.
What is object cache?
Let’s start from back to front. Object cache is, as the name suggests, a method of caching data. To break it down even further, for those who might not be familiar with the concept, caching involves storing frequently used data in high-speed memory to reduce server processing time and load.
Object caching is most commonly used to store the results of database queries and other expensive PHP operations as reusable objects in memory (RAM), reducing the need for repeated database access. Or, as Nathan put it more succinctly:
Object caching is going to take the PHP outputs of functions–it goes out and grabs some stuff out of the database, and holds that as an object.
Imagine a WooCommerce store with thousands of products. Without object caching, every product click could trigger a fresh database query. Yes, they happen in milliseconds, but they can pile up when thousands of people constantly request data.
With object caching, however, frequently accessed data is served from memory instead, cutting down on unnecessary database calls.
What is Redis?
So how can websites implement object cache? Some applications, like WordPress, can use it out of the box. However, such default solutions aren’t always persistent (lasting only for a single request) or optimized.
That’s where tools like Redis (REmote DIctionary Server) come in handy. Its technical definition is: a software solution that powers object caching by storing cached data in memory, making it persistent and significantly faster to access.
In other words, to move away from the dry, technical explanation, Redis keeps cached data around, unlike WordPress’ behavior, which only stores data for a single page load. That way, multiple requests (think hundreds or thousands) can benefit from the cached data.
Benefits of Redis and object cache
We already mentioned that one of the biggest benefits Redis has is that it makes cache persistent between requests.
However, that’s not all. It and object cache can be immensely helpful for your website, offering:
Improved performance: Object cache stores all data in RAM, where the access speeds are much faster than on a typical disk. If your site has many pages or elements that require a database query, you are likely to notice a boost in speed.
Reduced database load: Because your website doesn’t need to query the database as often, that will lessen the load on the database server. That lowers CPU and disk usage and improves stability during traffic spikes.
Increased scalability: Your site can handle more traffic without slowing down. With cache shared across requests, each visitor puts less strain on your server, allowing it to serve more concurrent visitors.
Support for complex data: Redis can store arrays, hashes, counters, queues, sessions, and other complex data structures.
As you can see, leveraging Redis and object cache can have a positive impact on how quickly your website loads and how much pressure it puts on the server.
With all of this said, to wrap up our blog on Redis and object cache, let’s take a look at a few things that new Redis users often misunderstand.
5 common Redis misconceptions
Redis is an extremely useful tool to have, but there are a few things that are often misconstrued about it. Some of these misconceptions are mostly harmless, while others can lead to website slowness and instability.
Redis is a database
Many people think that Redis is just another database. That has a grain of truth in it: Redis can write data to a disk, but it’s actually not a database. It’s optimized for speed and caching, and not long-term storage like a proper database management system (like MySQL).
Redis is designed to store temporary or frequently accessed data. It’s not ideal for storing heavy, canonical data, such as user or product information. In a pinch, it can act as a database, but we don’t recommend it.
Redis can fool visitors by serving outdated data
This is a genuine concern many people have, and while it is entirely possible, it doesn’t happen as often as one might think.
In reality, outdated (stale) data is served only as often as Redis’ configuration allows. With proper cache invalidation and TTL (time-to-live), you can avoid serving stale data. Furthermore, many modern applications, such as WordPress and WooCommerce, have safeguards in place to prevent such issues entirely. They will clear or refresh objects cached by Redis when content changes.
Redis is only for big sites
Would you say that sports shoes are only for athletes?
This misconception comes from the fact that Redis is often included in the larger plans that hosting companies offer. It does require dedicated memory and resources, and can sometimes prove too intense for smaller hosting plans (not ours, though).
Redis can benefit any site by reducing repeated database queries and improving response times. The size or complexity of the site doesn’t matter. What matters is if you want faster page loads and a less-stressed server.
Smaller sites may not see significant improvements (since they're already fast), but that doesn’t mean Redis is reserved only for the giants.
Redis is a replacement for WordPress caching plugins
We’ve heard this one so many times, we have a response locked and ready.
Redis is a performance tool that leverages object caching to reduce queries to MySQL, not a complete page caching solution.
-Ben Gabler, CPO, hosting.com
This means Redis handles object caching but can’t handle full-page or browser caching. Neither can it enable CDN integration. That’s where a caching plugin like WP Rocket (or its equivalent, depending on your application) comes in.
Solutions like WP Rocket act as a control center for caching, CDN integration, and general optimization, but Redis doesn’t replace them. In fact, it’s usually easier to manage Redis with one of those.
Small change, big performance win
Redis and object caching may seem daunting at first, but as you can see, their role is simple. Object caching reduces the database requests your site has to process, and Redis makes object caching itself persistent.
They both work towards making your website load faster, handle more traffic with ease, and remain stable under load. As simple as that.
If you’d like to see explanations like these live, register for our Office Hours livestreams and join us every Thursday at 2 p.m. EST. Ask a question about websites, hosting, WordPress, or agency work, or just watch to learn something new.
FAQ
How do I know if my WordPress site would actually benefit from Redis?
The sites that see the most meaningful improvement from Redis are those generating significant numbers of database queries per page load. Typically WooCommerce stores with large product catalogs, membership sites with user-specific content, or any site experiencing noticeable slowdowns under traffic.
A good first diagnostic is to use a tool like Query Monitor (a free WordPress plugin) to see how many database queries your pages are generating and how long they take. If you're seeing dozens or hundreds of queries per page load, object caching is likely to help noticeably.
Does Redis need to be configured and maintained after it's enabled?
For most WordPress sites, Redis is closer to set-and-forget once properly configured, but there are a few things worth keeping an eye on. Redis stores its cache in memory, which means it has a maximum memory allocation. When that limit is reached, it uses an eviction policy to decide which data to remove.
The default eviction behavior may not always match what's best for your site, so understanding your hosting provider's Redis configuration (or checking with their support) is worthwhile.
Are there alternatives to Redis for object caching in WordPress?
Yes. Memcached is the other well-established option, and it predates Redis. Both operate on the same core principle of storing data in memory to reduce database queries, but they have different characteristics.
Redis supports more complex data structures, can persist data to disk, and offers more fine-grained control over how cached items are managed. Memcached is simpler, extremely fast for straightforward key-value storage, and has a smaller memory footprint.
For most WordPress sites, either works well, and the choice often comes down to what your hosting provider supports.If your host offers both, Redis is generally the safer long-term choice.
If I flush the Redis cache to troubleshoot a problem, will my site go down or experience a significant slowdown?
Flushing the Redis cache won't take your site down, but you may notice a brief performance dip immediately afterward while the cache repopulates. When the cache is empty, every request has to go back to the database to fetch its data fresh. For most sites, this rebuilds quickly as visitors load pages and WordPress repopulates the cache automatically. On a high-traffic site, flushing during peak hours could temporarily increase database load noticeably, so if you have the flexibility, doing it during a low-traffic period is worth the small inconvenience.