### Caching queries, results and metadata

If you want to set a cache for query, result and metadata, you can specify this inside your `module.config.php`

```php
return [
    'doctrine' => [
        'configuration' => [
            'orm_default' => [
                'query_cache'       => 'filesystem',
                'result_cache'      => 'array',
                'metadata_cache'    => 'apc',
                'hydration_cache'   => 'memcached',
            ],
        ],
    ],
];
```

The previous configuration take in consideration different cache adapters. You can specify any other adapter that implements
the `Doctrine\Common\Cache\Cache` interface. Find more [here](http://doctrine-orm.readthedocs.org/en/latest/reference/caching.html).

#### Example with Redis

```php
return [
    'doctrine' => [
        'configuration' => [
            'orm_default' => [
                'query_cache'       => 'redis',
                'result_cache'      => 'redis',
                'metadata_cache'    => 'redis',
                'hydration_cache'   => 'redis',
            ],
        ],
    ],
];
```

In this case you have to specify a custom factory in your `service_manager` configuration to create a
`Redis` object:

```php
// module.config.php
return [
    'service_manager' => [
        'factories' => [
            __NAMESPACE__ . '\Cache\Redis' => __NAMESPACE__ . '\Cache\RedisFactory',
        ],
    ],
    'doctrine' => [
        'cache' => [
            'redis' => [
                'namespace' => __NAMESPACE__ . '_Doctrine',
                'instance'  => __NAMESPACE__ . '\Cache\Redis',
            ],
        ],
    ],
];
```

```php
// RedisFactory.php
namespace YourModule\Cache;

use Zend\ServiceManager\FactoryInterface;
use Zend\ServiceManager\ServiceLocatorInterface;

class RedisFactory implements FactoryInterface
{
    public function createService(ServiceLocatorInterface $serviceLocator)
    {
        $redis = new Redis();
        $redis->connect('127.0.0.1', 6379);

        return $redis;
    }
}
```

Read more about [Caching](http://doctrine-orm.readthedocs.org/en/latest/reference/caching.html).




### How to enable and configure Second Level Cache

```php
return [
    'doctrine' => [
        'configuration' => [
            'orm_default' => [
                'result_cache' => 'redis', // Second level cache reuse the cache defined in result cache
                'second_level_cache' => [
                    'enabled'               => true,
                    'default_lifetime'      => 200,
                    'default_lock_lifetime' => 500,
                    'file_lock_region_directory' => __DIR__ . '/../my_dir',
                    'regions' => [
                        'My\FirstRegion\Name' => [
                            'lifetime'      => 800,
                            'lock_lifetime' => 1000,
                        ],
                        'My\SecondRegion\Name' => [
                            'lifetime'      => 10,
                            'lock_lifetime' => 20,
                        ],
                    ],
                ],
            ],
        ],
    ],
];
```

You also need to add the `Cache` annotation to your model ([read more](http://doctrine-orm.readthedocs.org/en/latest/reference/second-level-cache.html#entity-cache-definition)).
Read more about [Second Level Cache](http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/second-level-cache.html).