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While Object Caching will store executed PHP which may or may not contain information retrieved from your database, it may not cache the majority of calls to your database. If after enabling Object Caching you have many database queries being performed, it’s time to cache the database queries themselves.

Database Caching assists with freeing up MySQL server resources taken by serving repeated queries returning the same data each time, so that it has more power to handle real dynamic data.

Cache your database and get better performance with W3 Total Cache Pro

Choosing a Method

For suggestions tailored to your hosting plan and recommendations on which Database Caching method to use, consider upgrading to W3 Total Cache Pro for access to the Statistics page.

Shared Server

In shared hosting platforms, you may only be able to cache files to a disk. In such cases, there is only one option available for Database Caching unless your hosting provider has a method listed under VPS / Dedicated Server or Multiple Servers available.


Disk-based caching should only be used when your site requires many expensive database queries, or your MySQL server is extremely slow. Using disk-based Database Caching is generally not recommended as it is usually slower than relying solely on MySQL to process queries as they are requested.

VPS / Dedicated Server

On WordPress VPS hosting and/or Dedicated hosting platforms you may use an in-memory caching solution rather than exclusively caching to disk. In-memory caching takes advantage of the much faster read/write speeds and lower latency of accessing data from system memory compared to disk-based alternatives.

Alternative PHP Cache (APC / APCu)

APC refers to Alternative PHP Cache which provides in-memory Opcode caching and a key-value store for looking up cached items. This is largely deprecated in favor of modern Opcode Caching mechanisms, as APC is not supported in the PHP 7.x branch.

APCu is similar to APC, though in order to support modern variants of PHP it is stripped of Opcode Caching and only provides the in-memory key-value store mechanisms. When paired with modern Opcode Caching mechanisms it can provide the functionality originally provided by APC, though it should only be used when you require having a limited cache size.

APC/APCu is not stable when a lot of memory allocated. In cases where you are caching a small amount of data, APC/APCu may be the ideal method for single-instance hosting platforms such as VPS or Dedicated hosting.


eAccelerator is an in-memory Opcode caching solution that supports the PHP 4.x and 5.x major versions. This is largely deprecated in favor of modern Opcode Caching mechanisms, as eAccelerator is not supported in the PHP 7.x branch.


XCache is an in-memory Opcode caching solution that supports up to the PHP 5.6 release. This is largely deprecated in favor of modern Opcode Caching mechanisms, as XCache is not supported in the PHP 7.x branch.

WinCache is an extension for Microsoft IIS which provides in-memory Opcode caching and currently supports up to IIS 10 as of 04/30/2019. Check the official Microsoft product page for the latest information.

Multiple Servers

If you have multiple hosting plans where one plan has root-level access, or if your hosting provider offers addons or bundles providing one of the following solutions, you may offload your in-memory caching to another server. This allows you to separate your actual site and caching solution between multiple servers to compliment each other, and allows for easier scaling to serve many users.


Memcached is a high-performance, distributed memory object caching system meant to speed up dynamic web applications by alleviating database load. It provides an in-memory key-value store for small chunks of arbitrary data (strings, objects) from the results of database calls, API calls, or page rendering.

Memcached is ideal for relatively small and static data, and as a result may be more efficient than Redis. It is also multithreaded, which may be a benefit when using a VPS or Dedicated Server with a large resource pool.


Redis is an in-memory data structure store which may be used as a database, cache, and message broker. Redis is somewhat of an industry-standard at the time of writing, and can be defined simply as a superset of Memcached when purely talking about similarities between each feature set.

Frequently Asked Questions

Enabling database caching didn’t improve my performance

First, examine your heaviest SQL queries and ensure those are being cached. Another issue can be that too much data is being transferred too frequently. You may want to check for the following:

  • Check if there are too many items in the wp_options table that contain autoload=’yes’
  • Ensure your cache hit rate is appropriate. If it appears to be too low:
    • This may indicate that the cache is being flushed. You may need to determine if a query is causing the cache to be flushed early.
    • Queries that are causing issues can be moved to a separate group so that they are not affected by the cache being flushed.

Can I use a MySQL Cluster?

With W3TC PRO you may use cluster of MySQL servers when a single MySQL instance can’t handle all your traffic.

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11 thoughts on “Choosing a Database Caching Method in W3 Total Cache

  1. W3TC DB Cluster and Pro Sub Discounts Questions

    I work for a non-profit with 12 WordPress websites and I have a few questions.

    Does the DB Cluster feature currently work? Some customers have reported issues recently in the forum.

    Each website has production, preprod, and dev instances. Would a Pro Subscription be required for the preprod and dev instances?

    Do you have a discount for non-profits?

    I posted this on Friday, January 5 at but haven’t heard back yet so I am asking here as well. Thanks.

  2. I have W3TC v2.5.0 with WP v6.3.2. Database Cache is enabled with memcached and the defaults. When I enable “Debug Mode: Database Cache” and log out, I always see 0 queries cached on any page like this:

    Db cache debug info:
    Total queries: 144
    Cached queries: 0
    Total query time: 1.5735

    Any tips on debugging this? “Never cache the following pages” is empty and we have many queries that don’t match the default “Ignored query stems,” “Reject query words,” and “Reject constants.” Page cache and Object cache debug information looks fine.

      • Thank you Marko. I am using both Object and DB caching with the same memcached instance. The memcached connectivity tests pass for both. I was able to see a non-zero Cached Queries value with “Don’t cache queries for logged in users” OFF and Page and Object cache OFF. I will gather more data and file a bug report if I need to. My main concern is why Db cache debug info: Cached queries: value has always been zero with W3TC across all of our WP instances. Page caching and Object caching debug info always looks more reasonable.

  3. W3 Total Cache Error: Files and directories could not be automatically created to complete the installation.

    db.php error can not install

    • Hello sahin,

      This means that your files/folders permissions need to be changed to allow W3 Total Cache to create files and folders needed to complete the installation as well as the drop-ins in wp-content such as:
      advanced-cache.php (Page Cache)
      db.php (Database Cache)
      object-cache.php (Object Caching)
      Please make sure to change the permission for files 644 and folders 755 on your host.

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