Local Storage Cache

Local Storage Cache for WordPress on Azure is located within the Environment variables of the App setting called WORDPRESS_LOCAL_STORAGE_CACHE_ENABLED, with the value set to true. If the value has been set to false, it’s most likely due to autoscaling adjustments that have been applied to the environment.

In an Azure WordPress setup, a Local Storage Cache refers to the caching mechanism that stores static assets, database queries, or entire page content locally within the Azure App Service instance. Here’s how it works and why it’s useful:

What Is Local Storage Cache in Azure WordPress?

Local Storage Cache for WordPress on Azure involves storing frequently accessed content directly on the App Service instance’s local storage. This cached content can be HTML, CSS, JavaScript files, images, or even cached database queries. The main goal is to reduce the load on your WordPress backend (like MySQL databases) and reduce repeated requests for the same resources, thereby improving response time for end users.

How Does Local Storage Cache Work in Azure?

1. Data Storage:
   • When a WordPress page is visited, the cache stores the generated page (HTML), scripts, and other static resources in the Azure App Service’s local storage.
   • If a subsequent user visits the same page, the cache can serve the stored version of the page directly from the local storage instead of regenerating it from scratch.
2. Cache Management:
   • Caching Plugins: Tools like W3 Total Cache or WP Super Cache manage this caching. These plugins enable local storage caching by storing pre-rendered page files within specific directories, typically in /wp-content/cache/.
   • Blob Storage or File Storage: For assets stored in blob storage (like media files), they might be served from the blob cache layer, reducing the need to access the App Service for every request.
3. Automatic Expiration and Refresh:
   • Cached content can expire after a specified period, or it can be refreshed if the content changes (e.g., a new blog post is published). Cache plugins generally handle this by invalidating outdated files and replacing them with the latest versions.
4. Types of Cached Data:
   • Static Asset Cache: HTML, CSS, and JavaScript files that don’t change often.
   • Database Query Cache: Repeated database queries are stored temporarily to reduce database load.
   • Full Page Cache: Entire page content is stored, reducing the need for PHP and database processing for each request.

Why Enable Local Storage Cache for Azure WordPress?

1. Faster Load Times: Serving cached assets locally means they load faster than if retrieved from a database or external storage.
2. Reduced Server Load: Fewer database queries and lower backend processing help manage the server load, particularly useful for handling high traffic.
3. Scalability: Local caching improves site performance, reducing the need to scale up resources, which could save on costs.

Considerations and Best Practices

1. Clear Cache on Updates: When you update your WordPress site, make sure the cache is cleared to prevent users from seeing outdated content.
2. Combine with Azure CDN: For global reach, combine local cache with Azure CDN to distribute content geographically and further improve speed for users outside your server’s region.
3. Use Azure Redis Cache (for Advanced Caching): For larger setups, consider using Azure Redis Cache, which adds distributed caching for more advanced scenarios, especially across multiple instances.

Enabling and configuring a Local Storage Cache for WordPress on Azure can greatly enhance site performance, especially when managed with cache plugins and caching best practices.