KEYS
Introduction and Use Case(s)
The KEYS
command in Redis is used to find all keys matching a given pattern. It is particularly useful for debugging or discovering key names within your database, especially in development environments. However, it should be used sparingly in production due to its potential impact on performance.
Syntax
KEYS pattern
Parameter Explanations
pattern
: A glob-style pattern to match keys against. Patterns can include special characters:*
matches zero or more characters.?
matches exactly one character.[abc]
matches any one of the characters inside the brackets.[a-z]
matches any character in the range.
Return Values
The KEYS
command returns an array of keys that match the specified pattern.
Example:
1) "key1"
2) "key2"
3) "anotherkey"
If no keys match, it returns an empty list.
Code Examples
dragonfly> SET key1 "value1"
OK
dragonfly> SET key2 "value2"
OK
dragonfly> SET anotherkey "value3"
OK
dragonfly> KEYS key*
1) "key1"
2) "key2"
dragonfly> KEYS *key
1) "anotherkey"
dragonfly> KEYS k?y1
1) "key1"
Best Practices
- Use in Development: The
KEYS
command is best used in development or debugging scenarios due to its potential to cause high latency by scanning the entire keyspace. - Alternative Commands: In production, prefer using
SCAN
as it performs incremental iterations over the keyspace, being more memory and CPU efficient. - Pattern Specificity: Be specific with the patterns to minimize the number of keys returned and reduce overhead.
Common Mistakes
- Large Databases: Running
KEYS
on a large dataset can block the server and degrade performance. Use it cautiously. - Misunderstanding Patterns: Ensure the correct use of wildcard characters in patterns to avoid unexpected results.
FAQs
How does KEYS
impact Redis performance?
Using KEYS
on a large dataset can block the Redis server, leading to increased latency and potential downtime for other operations. It scans the entire keyspace, which can be resource-intensive.
What are the alternatives to KEYS
for safer production use?
The SCAN
command is recommended for iterating through large datasets incrementally. It allows you to process keys in batches without blocking the server.