while(my @row = $res->fetchrow_array()) {

    my ($username, $product) = @row;
    
    # mark product as used
    if(!exists($agency_products{$user_agency{$username}}{$product})) {
        $agency_products{$user_agency{$username}}{$product} = 1;
        $user_products{$username}{$product} = 1;
    }
    
}