PHP Memcached getByKey() Function

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The Memcached::getByKey() function is an inbuilt function of Memcached class in PHP which is used to retrieve an item from a specific server. Functionally this function is equivalent to Memcached::get() function, except that the free-form server_key can be used to map the key to a specific server.

Syntax:

public Memcached::getByKey($server_key, 
    $key, $cache_cb = ?, $flags = ?): mixed

Required Parameters: This function accepts four parameters that are discussed below:

server_key: The key identifying the server to store the value on or retrieve it from.
key: The key of the item to fetch.
cache_cb: Read-through caching callback or null
flags: Flags to control the returned result. When the value of Memcached::GET_EXTENDED is given, it will return the CAS token.

Expected return value: For finding the value of a key from the specific server if we use Memcached::getByKey(), we can expect two type of values either the value stored in the cache or false otherwise. In case if key does not exist in the server Memcached::getResultCode() will return Memcached::RES_NOTFOUND as error.

Below examples illustrate the Memcached::getByKey() function in PHP:

Example 1:

PHP

echo "<pre>"; 
  
// Server & port details 
$server = '127.0.0.1'; 
$port = 11211; 
  
// Initiate a new object of memcache 
$memcacheD = new Memcached(); 
  
// Add server 
if ($memcacheD->addServer($server, $port)) { 
    echo "**  server added ** \n"; 
} 
else { 
    echo "** issue while creating a server **\n"; 
} 
  
// Set key & value with TTL 
$key = "GEEKSFORGEEKS1"; 
$value = "computer science portal"; 
$ttl = 3600; 
  
if ($memcacheD->addByKey( "serverkey", $key, $value, $ttl)) 
      echo "** added key-value (" . $key . ":" 
      . $value . ")to cache successfully!! **\n"; 
else 
      echo "** error while adding value to cache!! **\n"; 
  
// Get value of key 
echo "****   FETCHED VALUE   FOR KEY :" . $key . " ****\n"; 
$valD = $memcacheD->getByKey("serverKey", $key); 
var_dump($valD); 
  
?>

Output:

* server added **
** added key-value (GEEKSFORGEEKS1:computer science portal)to cache successfully!! **
**** FETCHED VALUE FOR KEY :GEEKSFORGEEKS1 ****
string(23) “computer science portal”

Example2:

PHP

<?php 
echo "<pre>"; 
  
// Server & port details 
$server = '127.0.0.1'; 
$port = 11211; 
  
// Initiate a new object of memcache 
$memcacheD = new Memcached(); 
  
// Add server 
if ($memcacheD->addServer($server, $port)) { 
    echo "**  server added ** \n"; 
} 
else { 
    echo "** issue while creating a server **\n"; 
} 
  
// Set key & value with TTL 
$key = "GEEKSFORGEEKS2"; 
$value = "computer science portal"; 
$ttl = 3600; 
  
if ($memcacheD->addByKey( "serverkey", $key, $value, $ttl))  
      echo "** added key-value (" . $key . ":" 
      . $value . ")to cache successfully!! **\n"; 
  
// Already added, try it once 
if ($memcacheD->addByKey( "serverkey", $key, $value, $ttl))  
      echo "** added key-value (" . $key . ":" 
      . $value . ")to cache successfully!! **\n"; 
else 
      echo "** error while adding value to cache!! **\n"; 
  
// Get value of key 
echo "****   FETCHED VALUE   FOR KEY :" . $key . " ****\n"; 
$valD = $memcacheD->getByKey("serverKey", $key); 
var_dump($valD); 
  
?> 

Output:

** server added **
** added key-value (GEEKSFORGEEKS2:computer science portal)to cache successfully!! **
** error while adding value to cache!! **
**** FETCHED VALUE FOR KEY :GEEKSFORGEEKS2 ****
string(23) “computer science portal”

Reference: https://www.php.net/manual/en/memcached.getbykey.php