Using the Cache component ¶

To use Redis for your application’s cache, you must configure the cache component to be an instance of yii\redis\Cache, in addition to configuring the connection (as described in the installation section):

return [
    // ...
    'components' => [
        // ...base `redis` component definition...
        'cache' => [
            'class' => yii\redis\Cache::class,
        ],
    ]
];

By default, yii\redis\Cache uses the globally-configured redis connection component.

If you plan on using Redis for more than one component, configure your connection directly on the cache component:

return [
    //....
    'components' => [
        // ...
        'cache' => [
            'class' => yii\redis\Cache::class,
            'redis' => [
                'class' => yii\redis\Connection::class,
                'hostname' => 'localhost',
                'port' => 6379,
                'database' => 0,
            ],
        ],
    ]
];

Note that the connection explicitly designates database 0 for the cache. To avoid inadvertent flushing of sessions or mutex locks, each component should be configured with a different database.

As a last resort, the yii\redis\Cache::$shareDatabase can be set to true to replace indiscriminate flushing (via the FLUSHDB command) with a combination of SCAN and sequential DEL commands. For applications with many cache keys, this can cause “flushes” to consume huge amounts of resources; the required time also scales linearly—if a single deletion typically takes 1ms, 100,000 keys would take at least 10 seconds (SCAN returns batches of 10, by default, and those are grouped into a single DEL command).

The cache provides all methods of the yii\caching\CacheInterface. If you want to access redis-specific methods that are not included in the interface, you can use them via yii\redis\Cache::$redis, which is an instance of yii\redis\ConnectionInterface:

Yii::$app->cache->redis->hset('mykey', 'somefield', 'somevalue');
Yii::$app->cache->redis->hget('mykey', 'somefield');
...

See yii\redis\Connection for a full list of available methods.