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SQLite Object Cache

By OllieJones

Performance & Optimization / Caching Solutions

SQLite Object Cache Review - In-Depth Analysis

SQLite Object Cache is a fast persistent object cache backend that enhances site performance by reducing database load. It uses SQLite and can be accelerated by APCu.

Performance Overview

WPS Score

6.64/10

User Rating

5/5 (based on 49+ reviews)

Active Installations

9,000+

Update Frequency

Below Average It is calculated using the weighted average of same category plugins.

Security Score

1 / 10 (Very Low Risk) It is calculated using the weighted average of all versions.

What It Does

SQLite Object Cache is a persistent object cache that helps improve your site's performance. It utilizes the SQLite3 extension and can optionally use igbinary and APCu extensions. This plugin is designed to reduce the workload on your MariaDB or MySQL database, allowing for faster content delivery.

By implementing a persistent object cache, your site can load essential information more quickly, which lightens the load on your database server. This plugin is particularly beneficial for sites running on a single web server that supports the necessary extensions.

APCu is an in-memory storage medium that significantly speeds up data retrieval for PHP programs like WordPress. When configured, it can enhance the performance of your caching, making your site operate more efficiently.

Other Notable Features

Here are a few other notable features of this free SQLite Object Cache plugin.

Apcu

Cache

Object Cache

Performance

SQLite

Screenshots

FAQ

Yes. To see the Settings page, choose Settings > Object Cache from the first site, or any site, in the multisite installation.

Putting your .sqlite files outside your site’s document root is good security practice. This is how you do it. If you define the constant WP_SQLITE_OBJECT_CACHE_DB_FILE in wp_config.php the plugin uses that for sqlite’s file pathname instead. For example, if wp-config.php contains this line

define( 'WP_SQLITE_OBJECT_CACHE_DB_FILE', '/tmp/mysite-object-cache.sqlite' );

your object cache data goes into the /tmp folder in a file named mysite-object-cache.sqlite.

You can also define WP_CACHE_KEY_SALT to be a hard-to-guess text string. Continuing the example, this line

define( 'WP_CACHE_KEY_SALT', 'qrstuv' );

causes your object cache data to go into the /tmp folder in a file named mysite-object-cache.qrstuv.sqlite.

Yes. You can use your OS’s memory map feature to access and share cache data with SQLite Memory-Mapped I/O. On some server configurations this allows multiple php processes to share cached data more quickly. In the plugin this is disabled by default. You can enable it by telling the plugin how many MiB to use for memory mapping. For example, this wp-config setting tells the plugin to use 32MiB.

define( 'WP_SQLITE_OBJECT_CACHE_MMAP_SIZE', 32 );

Notice that using memory-mapped I/O may not help performance in the highly concurrent environment of a busy web server. That is why it is disabled by default. Notice also that this kind of memory-mapping is not the same thing as the APCu cache.

Some sites occasionally generate error messages looking like this one:

Unable to execute statement: database is locked in /var/www/wp-content/object-cache.php:1234

This can happen if your server places your WordPress files on network-attached storage (that is, on a network drive). To solve this, store your cached data on a locally attached drive. See the question about storing your data in a more secure place. It also can happen in a very busy site.

Timeout errors can also happen if your Cached Data Size, or your site, is very large. Try reducing your Cached Data Size. If that doesn’t help eliminate timeout errors, try setting the WP_SQLITE_OBJECT_CACHE_TIMEOUT parameter in your wp-config.php file to something larger than the default 5000 milliseconds.