One of the most common use cases for HDEL
in Redis is when you want to remove one or more fields from a hash stored at a certain key. This can be useful, for example, when you are using Redis as a cache and need to invalidate certain parts of it without affecting others.
Java has several libraries that provide connectivity to a Redis instance including Jedis and Lettuce. Here's an example of how to use HDEL with Jedis:
import redis.clients.jedis.Jedis; public class Main { public static void main(String[] args) { // Connecting to Redis server on localhost Jedis jedis = new Jedis("localhost"); // Create a hash jedis.hset("hashKey", "field1", "value1"); jedis.hset("hashKey", "field2", "value2"); // Delete field1 from the hash jedis.hdel("hashKey", "field1"); // Print Remaining fields System.out.println(jedis.hgetAll("hashKey")); // Close connection jedis.close(); } }
In this example, first we connect to the Redis server running on localhost. Then we create a hash with two fields: 'field1' and 'field2'. The hdel
method is then used to delete 'field1' from the hash. Finally, we print out the remaining fields in the hash and close the connection.
1. What happens if I use HDEL on a field that doesn't exist? It will simply return 0 and not throw an error.
2. What happens if I use HDEL on a key that doesn't exist? The command will be ignored silently.
Dragonfly is fully compatible with the Redis ecosystem and requires no code changes to implement.