Memcached Storage Commands
- Memcached - CAS
- Memcached - Prepend Data
- Memcached - Append Data
- Memcached - Replace Data
- Memcached - Add Data
- Memcached - Set Data
Memcached Retrieval Commands
- Memcached - Incr/Decr
- Memcached - Delete Data
- Memcached - Delete Key
- Memcached - Get CAS Data
- Memcached - Get Data
Memcached Statistics Commands
- Memcached - Clear Data
- Memcached - Stats sizes
- Memcached - Stats Slabs
- Memcached - Stats Items
- Memcached - Stats
Memcached Useful Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
Memcached - Prepend Data
Memcached prepend command is used to add some data in an existing key. The data is stored before the existing data of the key.
Syntax
The basic syntax of Memcached prepend command is as shown below −
prepend 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 in 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. Data needs to be passed on the new pne 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 add some data in a key that does not exist. Hence, Memcached returns NOT_STORED. After this, we set one key and prepend data into it.
prepend tutorials 0 900 5 redis NOT_STORED set tutorials 0 900 9 memcached STORED get tutorials VALUE tutorials 0 14 memcached END prepend tutorials 0 900 5 redis STORED get tutorials VALUE tutorials 0 14 redismemcached END
Prepend Data Using Java Apppcation
To prepend data in a Memcached server, you need to use the Memcached prepend method.
Example
import net.spy.memcached.MemcachedCpent; pubpc class MemcachedJava { pubpc static void main(String[] args) { // Connecting to Memcached server on localhost MemcachedCpent mcc = new MemcachedCpent(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("Prepend to cache:"+mcc.prepend("tutorialspoint", "redis").isDone()); // get the updated key System.out.println("Get from Cache:"+mcc.get("tutorialspoint")); } }
Output
On compipng and executing the program, you get to see the following output −
Connection to server successful set status:true Get from Cache:memcached Prepend to cache:true Get from Cache:redismemcachedAdvertisements