Question

Im doing a database class in PHP and I want to make cache of the result of the querys in a associative array, My idea is to use the sql statment as the index of the cache array, its could be a good idea? or should I use a md5 from the sql?

class DB{
const HOST = 'localhost'; //Your Database Host!
const USER = 'user'; //Your Database Username!
const PASSWORD = 'pass'; //Your Database Password!
const DATABASE = 'database'; //Your Database Name!

private static $Instance;
private static $cache = array();

private function __construct(){
    self::$Instance = mysql_connect(self::HOST, self::USER, self::PASSWORD) or die("Could not connect to database server<br/><b>Error:</b>".mysql_error());
    mysql_select_db(self::DATABASE) or die("Could not connect to database<br/><b>Error:</b>".mysql_error());
    return self::$Instance;
}

public static function DB(){
    if(!isset(self::$Instance)){
      $c = __CLASS__; 
      new $c(); 
    }
    return self::$Instance;
}

public static function QueryUnique($query){
    $query = "$query LIMIT 1";
    //$h = md5($query);
    $h = $query;
    if(isset(self::$cache[$h]))return self::$cache[$h];

    $result = mysql_query($query, self::DB());
    self::$cache[$h] = mysql_fetch_array($result);
    return self::$cache[$h];
}

}

Good Day

Answer 1

Before you get too far through your implementation, you should know that mysql does its own query caching and it has several major advantages over your implementation:

• The cache is shared among all PHP requests.
• Cached results are automatically cleaned up when the table data changes.
• The cache is limited to a certain memory size (rarely-used queries will be dropped out of the cache)