An idea for DB server load balancing

If the application has a heavy load of reading queries and there are no problems with the application requirements,
a simple possible idea to balance the db server loading is to run the INSERT/UPDATE/ALTER queries in all the servers and run the SELECT queries in just one server (chosen randomly).
Have a look at the ‘loadBalancedQuery’ function: if the query modifies the db it will be executed in both server, otherwise in just one.

class BalancedDB extends Mysqli {

private function queryServer($query, $server = “mainServer” ) {
$db = DB::GetInstance($server);

public function loadBalancedQuery($query) {
if (
$this->queryServer( $query, “mainServer” );
$this->queryServer( $query, “secondaryServer” );

} else {
$this->queryServer( $query, rand(0,1) ? “mainServer”: “secondaryServer” );