Persistent Object Cache: How it Can Improve Your Website Performance (2024)

A persistent object cache is a powerful tool that significantly improves your WordPress website’s pagespeed performance.

Your users expect a fast-loading website, but seeing a slow WordPress website can ruin their experience and increase their bounce rate. A Persistent Object Cache can be used to solve this issue.

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You might be tempted to use Persistent Object Cache on your website, but first learn about persistent object cache in detail, how it works, and the benefits of using it in your WordPress website. Also, we will discuss the best practice for using persistence object cache – Redis and Memcached.

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What is a Persistent Object Cache?

Your wordpress website consists of PHP objects. These PHP objects are constantly built, initiated, and removed by your memory manager. These actions can overload your server, leading to a slow WordPress website. This issue can be solved by a persistent object caching mechanism.

Before going to the persistent object cache, you first need to understand what object cache is.

What is Object Cache?

An object cache is a built-in object-caching mechanism that is used to store the database query results in cache memory so that, the next time a query is needed, it can be quickly fetched from the object cache instead of querying the original database again.

A persistent object cache is known as a specialized server, such as Redis or Memcached, that is used to store your data in a way that persists beyond a single request or an entire session’s duration.

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In simple words, a persistent object cache is a server side caching technique where data is stored in a persistent storage such as an in-memory data structure store. It allows for a quicker retrieval of the data query.

For example, imagine your WordPress website has high organic traffic. Your website’s pagespeed will decrease due to server overloading. Implementing a persistent object caching technique can solve this issue by caching frequently accessed data queries in RAM.

How Does an Object Cache Work?

An object cache helps reduce frequently repeated queries by caching the query results from the first request. Let’s examine how it works in just three steps.

  1. Requesting Data

When your visit requests for certain data on your website for the first time, the browser sends an HTTP request to your web server.

  1. Check Cache

After receiving the HTTP request, it will check if the requested data is available in the object cache. This checking is usually performed by using a unique key. This key is based on the URL, database query, or other unique identifier.

  1. Cache Hit

If the requested data is present in the object cache, then it will directly be sent to the user. This process is known as cache hit.

If the requested data is not there in the object cache, then it will be served from the original database. This is known as a cache miss.

What is the Cache Hit Ratio?

The cache hit ratio monitors a cache’s efficiency. It measures how successfully an object cache serves the requested data to your user.

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The cache hit ratio is defined as the percentage of the total number of cache hits to the total number of requested data: cache hit & cache miss.

See more: BF Cache

Let’s understand with an example.

Cache Hit Ratio85%
Total number of requested data100
Cache Hit85
Cache Miss15

Difference Between Persistent Object Cache and Non-Persistent Object Cache

Let’s see the different types of object caching. The object cache is categorized into two types.

  1. Persistent Cache
  2. Non-Persistence Cache
Persistent CacheNon-Persistence Cache
DefinitionThe persistent object caching technique stores the data for a long time.
The data persists beyond a single request or entire session duration.
The Non-Persistence cache stores the data temporarily.
The data does not persist for the entire session.
CharacteristicsUse Redis cache and Memcached
Longer lifespan
Use an application’s memory.
Short lifespan.

What are the Benefits of Using a Persistent Object Cache on Your Website

Let’s see the two most important benefits of using a persistent object cache on your WordPress website.

  1. Reduce Your Database Workload

A persistent object cache is used to minimize the database queries by storing frequently accessed data in memory. Thus, it drastically reduces the database load, leading to a faster-loading WordPress website.

  1. Decoupling from External System

A persistent object cache provides buffer layers that allow the application to run even if the database ( primary data source) is slow or temporarily unavailable. Thus, it will improve your WordPress site’s performance.

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How Can You Check if Your WordPress Site Needs a Persistent Object Cache

A persistent object cache may not be required for all WordPress websites. But, a persistent object cache improves your website’s pagespeed performance, Only if your large website has lots of visitors.

To see whether your WordPress website requires a persistent object cache or not, you need to check your site health status by following the below steps:

  1. After logging into your WordPress dashboard, click on the Site Health screen link.
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  1. Wait for some time to finish the loading.
  1. After waiting for some time, you can see some suggestions to improve your site’s performance.
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  1. Click on Performance. In this tested website, a persistent object cache is required.
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How to Use Persistent Object Cache With WordPress

  • Redis

Redis (Remote Dictionary Server) is an open-source in-memory caching solution for data structures such as lists, strings, and hashes. Redis object cache is especially useful for session storage, database query caching, and other similar uses.

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There are a lot of WP caching plugins available that support Redis object cache such as Redis Object Cache, Object Cache Pro, WP Redis, and so on. Let’s see the installation process of the most popular Redis cache.

Check also: Web Caching Strategies

How You Can Install the Redis Object Cache Plugin?

To install the Redis cache in your WordPress site, you need to follow the steps:

Prerequisite:

  • RAM: A minimum of 2GB or higher RAM is required. If your WordPress server doesn’t have this, you need to upgrade it.
  • PHP: The PHP version needs to be more than 7.2.
  • Hosting: In the case of shared hosting, sometimes you need to upgrade your hosting package or switch hosts to install Redis object caching. If you are on managed wordpress hosting, it’s more likely that it will be available for free.

Steps:

  1. After logging into your WordPress admin, click on Add New Plugin in the Plugin section.
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  1. Search the Redis Object cache in the search box.
  1. Click on the Install Now.
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  1. After installing click on the Activate section.
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  1. After activating this wordpress object cache, click on Enable Object Cache.
  • Memcached:

Memcached is an open-source WordPress object caching system that stores strings and objects (resulting from database queries, API calls, or page rendering) in the server’s RAM.

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It consists of four major components:

  1. Client Software (collect the list of distributed Memcached servers)
  2. Client-Based Hashing Algorithm (Selete the server based on the keys)
  3. Server Software (Store that data (values and keys) in the hash table )
  4. Server Algorithm (decide when to delete the old data)

Several caching plugins available in the wordpress ecosystem, that support Memcached such as Speed Optimizer, Object Cache 4 Everyone, and many more.

Is RabbitLoader Compatible with Redis Object Cache and Memcached Object Cache?

As RabbitLoader is designed to be compatible with various wordpress cache plugins, it will be compatible with WP object cache plugins as well such as Redis persistent object cache and Memcached object cache.

Apart from the wordpress website, if you have a Laravel and PHP website, you can use RabbitLoader SDK because it is compatible with other caching plugins.

FAQ:

1. Which cache plugins are compatible with Memcached?

Most of the plugins that are available in the WordPress eco-system are compatible with Memcached such as RabbitLoader, w3 total cache, wp super cache, Litespeed cache, and many more.

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Persistent Object Cache: How it Can Improve Your Website Performance (2024)

FAQs

Persistent Object Cache: How it Can Improve Your Website Performance? ›

A persistent object cache is used to minimize the database queries by storing frequently accessed data in memory. Thus, it drastically reduces the database load, leading to a faster-loading WordPress website.

What is persistent object cache? ›

What is a Persistent Object Cache? Persistent Object Caches are specialized servers such as Redis or Memcached that provide an in-memory data structure store which is perfect for certain kinds of caching. In the WordPress world, the most common use for object caching is as a database or MySQL query cache.

How does caching improve performance? ›

A cache's primary purpose is to increase data retrieval performance by reducing the need to access the underlying slower storage layer. Trading off capacity for speed, a cache typically stores a subset of data transiently, in contrast to databases whose data is usually complete and durable.

What are the benefits of object cache? ›

By eliminating the need to access disks, Object Cache avoids seek time delays and can access data in microseconds. This improves performance for dynamic pages and logged-in users. It also provides a number of other features for developers looking to use it to manage queues, or perform custom caching of their own.

What is persistent cache? ›

The file cache is intended for intermediate term storage of documents or data objects. The libwww cache is a fully HTTP/1.1 compliant client side cache which honors all HTTP/1.1 cache directives and allows for disconnected operation.

What is the difference between persistent and non persistent cache? ›

Persistent cache - the permanent one

You can configure the cache to permanently save the data. By default, the cache is created as non-persistent, that is, the cache will be deleted once the session run is complete.

What is a persistent object? ›

In data terms, object persistence refers to an object that is not deleted until a need emerges to remove it from the memory. Some database models provide mechanisms for storing persistent data in the form of objects.

How does cache memory affect website performance? ›

To shorten page load times, browsers cache most of the content that appears on the webpage, saving a copy of the webpage's content on the device's hard drive. This way, the next time the user loads the page, most of the content is already stored locally and the page will load much more quickly.

Does clearing cache improve performance? ›

The cache and cookies should be cleared regularly for several reasons. Depending on your settings, the cache can grow quite big, use a lot of disk space on your computer and cause slow web browsing. The cache can also cause issues when viewing new versions of previously visited web pages.

What are the advantages and disadvantages of caching? ›

Caching can also reduce the network traffic, the server load, and the processing time of web resources. However, caching also has some drawbacks. Caching can introduce inconsistency, as the cached data may not reflect the latest changes or updates on the server.

Do I need object cache? ›

Persistent object caching is a must if you're looking to scale. Without it, your site's performance will slow down as its complexity and traffic increase. The same goes for logged in users and dynamic pages—object caching can help deliver a better and faster user experience.

What is the difference between object cache and page cache? ›

Page cache – Stores the previously generated code necessary to load a page. Object caching – Stores the results of queries to your site's database. Similar to regular page requests, queries can stack up and cause slowness on sites if too many are run at a time.

What is the main use of cache memory is to improve? ›

In summary, cache memory can improve system performance by reducing the time it takes for the processor to access frequently used data and instructions, resulting in faster processing speeds and better overall system performance.

How to set up persistent object cache? ›

To enable object caching via Redis on your site, install the Redis Object Cache plugin and open the Settings tab on your WordPress dashboard. Go to Redis → Enable Object Cache.

What is cache and persistence? ›

Caching or persistence are optimisation techniques for (iterative and interactive) Spark computations. They help saving interim partial results so they can be reused in subsequent stages. These interim results as RDDs are thus kept in memory (default) or more solid storages like disk and/or replicated.

Should I turn on object cache? ›

Persistent object caching is a must if you're looking to scale. Without it, your site's performance will slow down as its complexity and traffic increase. The same goes for logged in users and dynamic pages—object caching can help deliver a better and faster user experience.

What is the difference between shared cache and persistent cache? ›

You can share a named cache between transformations in the same or different mappings. Persistent cache. To save and reuse the cache files, you can configure the transformation to use a persistent cache. Use this feature when you know the lookup table does not change between session runs.

What is the difference between persist storage and cache? ›

While cache() uses the default storage level MEMORY_ONLY, persist() allows for the specification of various storage levels such as DISK_ONLY, MEMORY_AND_DISK, and more. This provides more flexibility as data can be stored in memory, disk, or a combination of both with persist() .

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