Question

Many of my classes require access to a database to do their work. For a while I’ve been doing something like the following:

// Create a (one) database object
$mysqli = new mysqli("host", "username", "password", "db");

// Pass database object into each new object that requires database interaction as follows
$car = new Car($data, $mysqli);
$plane = new Plane($data, $mysqli);
// etc

Then each class has a private $mysqli member which the passed in mysqli object is assigned to in the construct as follows:

class Car {

    private $mysqli;

    public function __construct($data, $mysqli) {

        $this->mysqli = $mysqli;

    }

}

Then class methods can use the mysqli object easily like this:

public function fuelLevel() {

    $this->mysqli->query("SELECT fuel_level FROM fuel_tank");

}

My question is, will I run into any performance issues if I were to create a few thousand of these objects? Am I correct in thinking that there is only technically one database connection in my entire application by doing so? Or should I be using references (pointers?) like below to avoid the feared performance overheads?

$car = new Car($data, &$mysqli);
$plane = new Plane($data, &$mysqli);

Answer 1

No, this cannot possibly cause any measurable performance impact. You are correct, there is a single connection object which you’re passing by reference. This level of optimization isn’t something you should be concerned with while developing in PHP.

You should absolutely not use call-time pass-by-reference (new Car($data, &$mysqli)), which is deprecated in PHP 5.3.