The HSTRLEN command in Redis is used to get the length of the value of a hash field stored at a key. It is commonly used when you need to know the size of a specific field within a hash, but not the entire hash. This can be particularly useful for storing and retrieving complex data structures like user profiles or sessions where each field might have different lengths.
Here's an example using the go-redis client library:
In this code, we first connect to the Redis server running on localhost at port 6379. We then set a hash field 'username' to 'myLongUsername' in the hash at key 'userProfile'. The HSTRLEN command is used to get the length of the value stored at the field 'username'.
Q: What if the key or field doesn't exist? A: If the key or field does not exist, Redis' HSTRLEN command returns 0.
Q: Does HSTRLEN change the expiration time of the key? A: No, HSTRLEN is a read operation and does not change the expiry time of the key.