Memcached get command is used to get the value stored at key. If the key does not exist in Memcached, then it returns nothing.

Syntax

The basic syntax of Memcached get command is as shown below −

get key

Example

In the following example, we use tutorialspoint as the key and store memcached in it with an expiration time of 900 seconds.

set tutorialspoint 0 900 9
memcached
STORED
get tutorialspoint
VALUE tutorialspoint 0 9
memcached
END

Get Data Using Java Application

To get data from a Memcached server, you need to use the Memcached get method.

Example

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 sucessfully");
      System.out.println("set status:"+mcc.set("tutorialspoint", 900, "memcached").done);

     // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));
   }
}

Output

On compiling and executing the program, you get to see the following output −

Connection to server successfully
set status:true
Get from Cache:memcached

Memcached delete command is used to delete an existing key from the Memcached server.

Syntax

The basic syntax of Memcached delete command is as shown below −

delete key

If the key is successfully deleted, then it returns DELETED. If the key is not found, then it returns NOT_FOUND, otherwise it returns ERROR.

Example

In this example, we use tutorialspoint as a key and store memcached in it with an expiration time of 900 seconds. After this, it deletes the stored key.

set tutorialspoint 0 900 9
memcached
STORED
get tutorialspoint
VALUE tutorialspoint 0 9
memcached
END
delete tutorialspoint
DELETED
get tutorialspoint
END
delete tutorialspoint
NOT_FOUND

Delete Data Using Java Application

To delete data from a Memcached server, you need to use the Memcached delete method.

Example

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("tutorialspoint", 900, "memcached").done);

      // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));

      // delete value from cache
      System.out.println("Delete from Cache:"+mcc.delete("tutorialspoint").isDone());

      // check whether value exists or not
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));
   }
}

Output

On compiling and executing the program, you get to see the following output −

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

Memcached stats items command is used to get items statistics such as count, age, eviction, etc. organized by slabs ID.

Syntax

The basic syntax of Memcached stats items command is as shown below −

stats items

Example

stats items
STAT items:1:number 1
STAT items:1:age 7
STAT items:1:evicted 0
STAT items:1:evicted_nonzero 0
STAT items:1:evicted_time 0
STAT items:1:outofmemory 0
STAT items:1:tailrepairs 0
STAT items:1:reclaimed 0
STAT items:1:expired_unfetched 0
STAT items:1:evicted_unfetched 0
END

Memcached incr and decr commands are used to increment or decrement the numeric value of an existing key. If the key is not found, then it returns NOT_FOUND. If the key is not numeric, then it returns CLIENT_ERROR cannot increment or decrement non-numeric value. Otherwise, ERROR is returned.

Syntax – incr

The basic syntax of Memcached incr command is as shown below −

incr key increment_value

Example

In this example, we use visitors as key and set 10 initially into it, thereafter we increment the visitors by 5.

set visitors 0 900 2
10
STORED
get visitors
VALUE visitors 0 2
10
END
incr visitors 5
15
get visitors
VALUE visitors 0 2
15
END

Syntax – decr

The basic syntax of Memcached decr command is as shown below

decr key decrement_value

Example

set visitors 0 900 2
10
STORED
get visitors
VALUE visitors 0 2
10
END
decr visitors 5
5
get visitors
VALUE visitors 0 1
5
END

Incr/Decr Using Java Application

To increment or decrement data in a Memcached server, you need to use Memcached incr or decr methods respectively.

Example

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 sucessfully");
      System.out.println("set status:"+mcc.set("count", 900, "5").isDone());

      // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("count"));

      // now increase the stored value
      System.out.println("Increment value:"+mcc.incr("count", 2));

      // now decrease the stored value
      System.out.println("Decrement value:"+mcc.decr("count", 1));

      // now get the final stored value
      System.out.println("Get from Cache:"+mcc.get("count"));
   }
}

Output

On compiling and executing the program, you get to see the following output −

Connection to server successfully
set status:true
Get from Cache:5
Increment value:7
Decrement value:6
Get from Cache:6

Memcached delete command is used to delete an existing key from the Memcached server.

Syntax

The basic syntax of Memcached delete command is as shown below −

delete key [noreply]

Output

CAS command may produce one of the following result −

• DELETED indicates successful deletion.

• ERROR indicates error while deleting data or wrong syntax.

• NOT_FOUND indicates that the key does not exist in the Memcached server.

Example

In this example, we use tutorialspoint as a key and store memcached in it with an expiration time of 900 seconds. After this, it deletes the stored key.

set tutorialspoint 0 900 9
memcached
STORED
get tutorialspoint
VALUE tutorialspoint 0 9
memcached
END
delete tutorialspoint
DELETED
get tutorialspoint
END
delete tutorialspoint
NOT_FOUND

Delete Data Using Java Application

To delete data from a Memcached server, you need to use the Memcached delete method.

Example

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("tutorialspoint", 900, "World''s 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("tutorialspoint value in cache - " + mcc.get("tutorialspoint"));

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

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

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

         // Shutdowns the memcached client
         mcc.shutdown();

      }catch(Exception ex)
         System.out.println(ex.getMessage());
   }
}

Output

On compiling and executing the program, you get to see the following output −

Connection to server successful
set status:true
tutorialspoint value in cache - World''s largest online tutorials library
delete status:true
tutorialspoint value in cache - null

Memcached append command is used to add some data in an existing key. The data is stored after the existing data of the key.

Syntax

The basic syntax of Memcached append command is as shown below −

append key flags exptime bytes [noreply]
value

The keywords in the syntax are as described below−

• key − It is the name of the key by which data is stored and retrieved from Memcached.

• flags − It is the 32-bit unsigned integer that the server stores with the data provided by the user, and returns along with the data when the item is retrieved.

• exptime − It is the expiration time in seconds. 0 means no delay. If exptime is more than 30 days, Memcached uses it as a UNIX timestamp for expiration.

• bytes − It is the number of bytes in the data block that needs to be stored. This is the length of the data that needs to be stored in Memcached.

• noreply (optional) − It is a parameter that informs the server not send any reply.

• value − It is the data that needs to be stored. The data needs to be passed on the new line after executing the command with the above options.

Output

The output of the command is as shown below −

STORED

• STORED indicates success.

• NOT_STORED indicates the key does not exist in the Memcached server.

• CLIENT_ERROR indicates error.

Example

In the following example, we try to add some data in a key that does not exist. Hence, Memcached returns NOT_STORED. After this, we set one key and append data into it.

append tutorials 0 900 5
redis
NOT_STORED
set tutorials 0 900 9
memcached
STORED
get tutorials
VALUE tutorials 0 14
memcached
END
append tutorials 0 900 5
redis
STORED
get tutorials
VALUE tutorials 0 14
memcachedredis
END

Append Data Using Java Application

To append data in a Memcached server, you need to use the Memcached append method.

Example

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("tutorialspoint", 900, "memcached").isDone());

      // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));

      // now append some data into existing key
      System.out.println("Append to cache:"+mcc.append("tutorialspoint", "redis").isDone());

      // get the updated key
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));
   }
}

Output

On compiling and executing the program, you get to see the following output −

Connection to server successful
set status:true
Get from Cache:memcached
Append to cache:true
Get from Cache:memcachedredis

Memcached set command is used to set a new value to a new or existing key.

Syntax

The basic syntax of Memcached set command is as shown below −

set key flags exptime bytes [noreply]
value

The keywords in the syntax are as described below −

• key − It is the name of the key by which data is stored and retrieved from Memcached.

• flags − It is the 32-bit unsigned integer that the server stores with the data provided by the user, and returns along with the data when the item is retrieved.

• exptime − It is the expiration time in seconds. 0 means no delay. If exptime is more than 30 days, Memcached uses it as UNIX timestamp for expiration.

• bytes − It is the number of bytes in the data block that needs to be stored. This is the length of the data that needs to be stored in Memcached.

• noreply (optional) – It is a parameter that informs the server not to send any reply.

• value − It is the data that needs to be stored. The data needs to be passed on the new line after executing the command with the above options.

Output

The output of the command is as shown below −

STORED

• STORED indicates success.

• ERROR indicates incorrect syntax or error while saving data.

Example

In the following example, we use tutorialspoint as the key and set value Memcached in it with an expiration time of 900 seconds.

set tutorialspoint 0 900 9
memcached
STORED
get tutorialspoint
VALUE tutorialspoint 0 9
Memcached
END

Set Data Using Java Application

To set a key in Memcached server, you need to use Memcached set method.

Example

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 sucessfully");
      System.out.println("set status:"+mcc.set("tutorialspoint", 900, "memcached").done);

      // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));
   }
}

Output

On compiling and executing the program, you get to see the following output −

Connection to server successfully
set status:true
Get from Cache:memcached

Memcached is an open source, high-performance, distributed memory caching system intended to speed up dynamic web applications by reducing the database load. It is a key-value dictionary of strings, objects, etc., stored in the memory, resulting from database calls, API calls, or page rendering.

Memcached was developed by Brad Fitzpatrick for LiveJournal in 2003. However, it is now being used by Netlog, Facebook, Flickr, Wikipedia, Twitter, and YouTube among others.

The key features of Memcached are as follows −

• It is open source.

• Memcached server is a big hash table.

• It significantly reduces the database load

• It is perfectly efficient for websites with high database load.

• It is distributed under Berkeley Software Distribution (BSD) license.

• It is a client-server application over TCP or UDP.

Memcached is not −

• a persistent data store

• a database

• application-specific

• a large object cache

• fault-tolerant or highly available

Memcached replace command is used to replace the value of an existing key. If the key does not exist, then it gives the output NOT_STORED.

Syntax

The basic syntax of Memcached replace command is as shown below −

replace key flags exptime bytes [noreply]
value

The keywords in the syntax are as described below −

• key − It is the name of the key by which data is stored and retrieved from Memcached.

• flags − It is the 32-bit unsigned integer that the server stores with the data provided by the user, and returns along with the data when the item is retrieved.

• exptime − It is the expiration time in seconds. 0 means no delay. If exptime is more than 30 days, Memcached uses it as a UNIX timestamp for expiration.

• bytes − It is the number of bytes in the data block that needs to be stored. This is the length of the data that needs to be stored in the Memcached.

• noreply (optional) − It is a parameter that informs the server not to send any reply.

• value − It is the data that needs to be stored. The data needs to be passed on the new line after executing the command with the above options.

Output

The output of the command is as shown below −

STORED

• STORED indicates success.

• NOT_STORED indicates the data is not stored in Memcached.

Example

In the following example, we use ‘key’ as the key and store memcached in it with an expiration time of 900 seconds. After this, the same key is replaced with the value ‘redis’.

add key 0 900 9
memcached
STORED
get key
VALUE key 0 9
memcached
END
replace key 0 900 5
redis
get key
VALUE key 0 5
redis
END

Replace Data Using Java Application

To replace data in a Memcached server, you need to use the Memcached replace method.

Example

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 sucessfully");
      System.out.println("set status:"+mcc.set("tutorialspoint", 900, "memcached").done);

      // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));

      // now replace the existing data
      System.out.println("Replace cache:"+mcc.replace("tutorialspoint", 900, "redis").done);

      // get the updated data
      System.out.println("Get from Cache:"+mcc.get("tutorialspoint"));
   }
}

Output

On compiling and executing the program, you get to see the following output −

Connection to server successfully
set status:true
Get from Cache:memcached
Replace cache:true
Get from Cache:redis