[Memcache] Login question

[QuietWhistler]

Hello everyone,

I have a couple of questions about Memcache. What I want to do is using memcache for user login, so when a user logs in, a memcache variable (array) is created. Here's the function:

[code]function login( $sUsername, $sPassword )
{
    $oMemcache = clsMem::getMem();
    if( $oMemcache->get( md5( $sUsername ) ) == "" )
    {
        $oSql = new Mysql();
        $oSql->query( "SELECT id, username, permissions FROM users WHERE username = '" . $sUsername . "' AND password = '" . md5( $sPassword ) . "'" );
        if( $oSql->fetchNumRows() == 1 )
        {
            $aUserInfo = $oSql->fetchArray( MYSQL_ASSOC );
            $oMemcache->set( md5( $sUsername ), $aUserInfo, false, 0 );
            session_start();
            $_SESSION[ "username" ] = md5( $sUsername );
        }
    }
}[/code]

Now my questions;

1. Is Memcache safe enough to use it for user login?
2. Is this faster than getting information from the database directly?