Getting All Keys using PHP Redis (Detailed Guide w/ Code Examples)

Use Case(s)

PHP Redis keys method is commonly used to retrieve all keys matching a certain pattern in a Redis database. This can be useful in several scenarios such as debugging, maintenance tasks, or when you need to manipulate set of data identified by similar key patterns.

Code Examples

Example 1: Get all keys

In this example, we will get all the keys in our Redis instance. The asterisk (*) is a wildcard that matches all keys.

$redis = new Redis();
$redis->connect('localhost', 6379);
$allKeys = $redis->keys('*');
print_r($allKeys);

Example 2: Get keys with a specific pattern

In this case, we're looking for keys that start with 'user':

$redis = new Redis();
$redis->connect('localhost', 6379);
$userKeys = $redis->keys('user*');
print_r($userKeys);

The 'user*' pattern will match any keys that start with 'user'.

Best Practices

• Be careful when using the keys command in a production environment, especially with large databases and broad patterns, as it may degrade performance.
• If possible, use the SCAN command instead of KEYS. SCAN provides a cursor-based iterator which is more efficient and doesn't block the server.

Common Mistakes

• Using KEYS in production environments: The KEYS command can negatively impact performance on large databases, so it's not recommended for production environments. Instead, consider using SCAN or maintain an index of your keys in a separate data structure.
• Ignoring return types: The KEYS command returns an array of strings representing the matching keys or FALSE if there are no keys. Always ensure to handle these return types correctly in your application.

FAQs

Q: Can I use patterns with the Redis keys method?

A: Yes, you can use patterns when retrieving keys. For example, 'user*' will match any keys that start with 'user'.