Finding keys in a Redis database matching a certain pattern is useful when you want to perform a mass operation on these keys, or need to filter keys based on specific criteria.
Let's assume we have a few keys such as user:1, user:2, user:3 and we're looking for all keys starting with 'user'.
The Predis client library can be used to connect PHP with Redis:
$client = new Predis\Client();
$keys = $client->keys('user:*');
keys method of the Predis client object is used to fetch all keys that match a given pattern. The '*' character is a wildcard that matches any sequence of characters.
- Since using KEYS command can be expensive in production as it might lead to blocking the entire Redis instance while scanning keys, consider using SCAN if possible.
- Always limit the number of keys being fetched at one time to prevent memory issues.
- Using the wrong type of wildcard can lead to unexpected results. Be sure you understand how wildcards work in Redis.
- Forgetting that key scanning in Redis is case-sensitive.
- Q: Can I use multiple patterns in a single KEYS command?
A: No, the Redis KEYS command only supports a single pattern.
- Q: What happens if there are no keys matching the pattern?
A: The KEYS command returns an empty list if no keys match the pattern.
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