Memcached - Delete Key

Memcached delete command is used to delete an existing key from the Memcached server. It means it removes an item from the cache if it exists.

Syntax

Here,

key: It is the key data stored and retrieved from Memcached.

noreply: It is an optional parameter. It is used to inform the server not to send any reply.

Return Value

This command will return the following value:

DELETED: Means successful deletion.

ERROR: It shows error while deleting data or when the syntax is wrong.

NOT_FOUND: shows that the key does not exist in the Memcached server.

Example in Ubuntu

Let's see an example for the delete command. Here we will use 'city' as the key and store 'bangalore' in it with the expiration of time 900 seconds. After this, delete command is used to delete the key 'city.'

set city 0 900 9
bangalore
STORED
get city
VALUE city 0 9
bangalore
END
delete city
DELETED
get city
END
delete city
NOT_FOUND

Example in Windows:

set city 0 900 9
bangalore
STORED
get city
VALUE city 0 9
bangalore
END
delete city
DELETED
get city
END
delete city
NOT_FOUND

Memcached Server:

Memcached Client:

Delete data using Java Application

Let's consider Memcached server is running on host 127.0.0.1 and port 11211. Here, we will use delete() method to delete the data from a Memcached server.

Example 1

import net.spy.memcached.MemcachedClient;
public class MemcachedJava {
   public static void main(String[] args) {
      
      // Connecting to Memcached server on localhost
      MemcachedClient mcc = new MemcachedClient(new
      InetSocketAddress("127.0.0.1", 11211));
      System.out.println("Connection to server successful");
      System.out.println("set status:"+mcc.set("city", 900, "bangalore").done);
      
      // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("city"));
      
      // delete value from cache
      System.out.println("Delete from Cache:"+mcc.delete("city").isDone());
      
      // check whether value exists or not
      System.out.println("Get from Cache:"+mcc.get("city"));
   }
}

Output:

Connection to server successful
set status: true
Get from Cache: Bangalore
Delete from Cache: true
Get from Cache: null

Example 2

import java.net.InetSocketAddress;
import java.util.concurrent.Future;

import net.spy.memcached.MemcachedClient;

public class MemcachedJava {
   public static void main(String[] args) {
   
      try{
   
         // Connecting to Memcached server on localhost
         MemcachedClient mcc = new MemcachedClient(new InetSocketAddress("127.0.0.1", 11211));
         System.out.println("Connection to server sucessful.");

         // add data to memcached server
         Future fo = mcc.set("javatpoint", 900, "largest online tutorials library");

         // print status of set method
         System.out.println("set status:" + fo.get());

         // retrieve and check the value from cache
         System.out.println("javatpoint value in cache - " + mcc.get("javatpoint"));

         // try to delete data with existing key
         Future fo = mcc.delete("javatpoint");

         // print status of delete method
         System.out.println("delete status:" + fo.get());

         // retrieve and check the value from cache
         System.out.println("javatpoint value in cache - " + mcc.get("codingground"));

         // Shutdowns the memcached client
         mcc.shutdown();
         
      }catch(Exception ex)
         System.out.println(ex.getMessage());
   }
}

Output:

Connection to server successful
set status:true
javatpoint value in cache - largest online tutorials library
delete status:true
javatpoint value in cache - null

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