Memcached tutorial part 1 - installation , examples

If you don't know what memcached is, ask uncle google ; ) In short it's a memory caching system that allows to reduce database load by putting values into RAM. Ok so installation on debian/ubuntu is as simple as that :

sudo apt-get install memcached php5-memcached

Afret installation you can check if memcached is working:

netstat -tap | grep memcached

You should get something like this:

tcp        0      0 localhost:11211         *:*                     LISTEN      1547/memcached 

By default deamon is listening on port 11211 You can change it by modifying config file : /etc/memcached.conf If everything works fine we can try it out :) You put value in cache by using 'set' method to read the value you have to know the key name and use 'get' method.

m = new Memcached;
$m->addServer('127.0.0.1', 11211);

$foo = "foo";

$m->set('f',$foo);
var_dump($m->get('f'));

$m->delete('f');
var_dump($m->get('f'));

output:

string(3) "foo"
bool(false)

Ok so the same with query :

$sql = "select count(id) as count from test.test";
$res = mysql_query($sql);
$row = mysql_fetch_assoc($res);
$count = $row['count'];
var_dump($count);
$m->set(md5($sql),$count);

var_dump($m->get(md5($sql)));

output:

string(1) "7"
string(1) "7"

So now we can create simple caching function :

function memQuery($sql,$m){

    $key = md5($sql);
    var_dump($m->get($key));

    if($m->get($key)===FALSE){

        echo "mysql:";
        $res = mysql_query($sql);
        $row = mysql_fetch_assoc($res);
        $m->set($key,$row);//store the result
        return $row;

    }else{
        echo "mysql:";
        return $m->get($key);
    }
}

In next part I'm gonna show some administration issues.