Configuration

Cache configurations

Unfortunately in TYPO3, all ext_localconf.php files of the extensions are loaded after the instance-specific configuration from config/system/settings.php and config/system/additional.php. This enables extensions to overwrite cache configurations already done for the instance. All extensions should avoid this situation and should define the very bare minimum of cache configurations. This boils down to define the array key to populate a new cache to the system. Without further configuration, the cache system falls back to the default backend and default frontend settings:

<?php

$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['myext_mycache']
    ??= [];

Extensions, like Extbase, define default caches this way, giving administrators full freedom for specific and possibly quicker setups (for example, a memory-driven cache for the Extbase reflection cache).

Administrators can overwrite specific settings of the cache configuration in config/system/settings.php or config/system/additional.php. Here is an example configuration to switch pages to the Redis backend using database 3:

<?php

use TYPO3\CMS\Core\Cache\Backend\RedisBackend;

$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['pages'] = [
    'backend' => RedisBackend::class,
    'options' => [
        'database' => 3,
    ],
];

Some backends have mandatory as well as optional parameters (which are documented in the Cache backends section). If not all mandatory options are defined, the specific backend will throw an exception, if accessed.

How to disable specific caches

During development it can be convenient to disable certain caches. This is especially helpful for central caches like the language or autoloader cache. This can be achieved by using the null backend as storage backend.

Example configuration to switch the extbase_reflection cache to use the null backend:

<?php

use TYPO3\CMS\Core\Cache\Backend\NullBackend;

$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']
    ['extbase_reflection']['backend'] = NullBackend::class;