We do everything to optimize the WordPress site. From enabling page cache, optimizing CSS, JS code, and implementing compression. Even after doing all possible optimizations what can we do if WordPress php scripts execution itself causes decreased performance?
And, here comes the role of Object cache. In object cache, we cache the results of the frequently executing PHP queries. This dramatically skips duplicate query executions and reduces server CPU load. And we can immediately feel the performance differences.
Currently, there are two popular object cache methods in trends, the first is Redis and the second is Memcached. Both are good and have their own user base.
In this article, we will explore the similarities, differences, and pros and cons of each, and ultimately determine which is the better option for WordPress object caching.
What is Object Cache and How it Works?
The object cache is a feature in the WordPress cache system that stores frequently accessed data in memory to improve website performance. It intercepts requests for data and returns cached objects instead of querying the database, reducing server load and improving response time.
Object caching is a vital aspect of caching in WordPress, enabling the storage of frequently accessed data in memory for quick retrieval, reducing database queries, and consequently improving overall site speed. Two popular object cache methods that have gained significant traction are Redis and Memcached.
Object cache support by the hosting server is necessary to enable it for your WordPress site. Either it can be enabled by using configuring open-source object cache software on VPS or by installing an object cache plugin in feature supported WordPress website.
Why Object Cache is Needed?
The need for an object cache can be understood by asking this question: “Why wordpress should execute the same database query for thousands of visitors when we have to send them the same result?”
Object caching plays a crucial role in optimizing WordPress performance by storing frequently requested database queries, API responses, and other computed data in memory.
Traditional database queries can be resource-intensive, slowing down the loading time of web pages. By caching objects in memory, subsequent requests can be served much faster, reducing server load and improving overall user experience.
Object caching is particularly beneficial for frequently accessed data, such as the output of complex database queries or dynamically generated content. This can include user profiles, search results, product information, and more.
By storing database objects in memory, WordPress can quickly retrieve them for subsequent requests, eliminating the need to redo expensive database query execution or computations repeatedly.
Benefits of Using Object Cache in WordPress
- Object caching stores frequently accessed data in memory, eliminating the need to regenerate it each time, leading to faster content delivery.
- By storing data in memory, the object cache reduces the number of database queries, easing the burden on the server.
- With caching, the server can respond quickly to user requests, accommodating more simultaneous visitors without straining resources.
- Caching in memory results in near-instant data access, minimizing delays and ensuring a more responsive user experience.
- During sudden spikes in traffic, the object cache helps maintain site stability by reducing the server workload.
- Quicker page loads and reduced latency contribute to a smoother and more enjoyable browsing experience for website visitors.
Redis vs Memcached: Quick Overview
Redis and Memcached are widely used open-source, in-memory data stores. While both are user-friendly and deliver excellent performance, they do have distinct characteristics that should be considered when selecting a caching engine. Memcached emphasizes simplicity, whereas Redis provides a comprehensive feature set, making it suitable for diverse use cases.
Comparison of Redis and Memcached Object Cache
Here is a quick feature comparison table, that will give you a clear idea of which one is suitable for your project.
| Features | Redis | Memcached |
|---|---|---|
| Key-value pair data stores | Yes | Yes |
| Supports Data Partitioning | Yes | Yes |
| Sub-millisecond latency | Yes | Yes |
| NoSQL family | Yes | Yes |
| Open-source | Yes | Yes |
| Supported Languages | Majority of programming languages | Majority of programming languages |
| DataTypes Supported | Strings, lists, sets, sorted sets, hashes, and more | Simple key-value pairs |
| Memory Management | Swap values to disk when memory fully occupied | Strictly in-memory with an extension for disk storage |
| Data Size Limits | Up to 512 MB (strings) | Up to 1 MB |
| Data Persistence | RDB snapshot and AOF Log persistence policies | No data persistence |
| Cluster Mode | Supports distributed cache (Clustering) | Achieved on client-side using consistent hashing |
| Multi-Threading | Doesn’t support multi-threading | Supports multi-threading |
| Scaling | Horizontally scalable | Vertically scalable, requires effort for clustering |
| Data replication | Supports data replication out of the box | No data replication |
| Supported Eviction Policies | Various options like LRU, random, TTL, and more | LRU |
| Transaction Management | Supports transactions | No transaction support |
| Recommendation | Larger applications with complex data | Smaller and static data, multi-threading applications |
Now, here is a detailed comparison of both methods,
Architecture and Data Storage
Redis and Memcached are both open-source in-memory data stores. Redis offers a wide range of data types, along with advanced features such as persistence, replication, and clustering. It can store data in both memory and on disk, ensuring quick retrieval and persistence of cached data across restarts. On the other hand, Memcached is more straightforward and only supports key-value pairs without built-in persistence or data replication features.
Scalability
Redis excels in scalability, supporting data sharding and partitioning across multiple instances, making it ideal for high-traffic websites and large user bases. On the other hand, Memcached is also scalable but lacks certain advanced features of Redis, making it more suitable for smaller to medium-scale projects with potentially limited capacity for handling extensive data and traffic.
Performance
Redis offers outstanding performance, thanks to its advanced data structures and versatility with multiple data types, making it an ideal choice for object caching in WordPress. On the other hand, Memcached stands out for its simplicity and lightning-fast performance, but its limited support for data structures might not be suitable for more complex caching requirements.
Ease of Use and Integration
Redis provides a robust feature set, which can make its setup and configuration slightly more complex than Memcached. However, WordPress plugins offer simplified integration for both Redis and Memcached, making them accessible caching solutions for developers.
Review: Which is Better?
The decision between Redis and Memcached as the preferred object cache method in WordPress depends on the specific needs of your website or application.
Choose Redis If:
- You require advanced data structures and operations in your caching mechanism.
- Your project is large-scale with high traffic and demands excellent scalability.
- Data persistence and replication are crucial for your caching strategy.
- You have experience with setting up and managing more complex caching systems.
Choose Memcached If:
- You seek a simple and straightforward caching solution for smaller to medium-scale projects.
- Your focus is on raw performance and you do not need advanced data structures or persistence features.
- You are new to caching and need an easy-to-use option.
Conclusion
If you prioritize advanced features, scalability, and data persistence, Redis might be the better option. On the other hand, if you desire a straightforward and high-performance caching solution, Memcached could be the more suitable choice. Regardless of the method chosen, implementing object caching in WordPress is essential for enhancing website performance and delivering a seamless user experience.
