Вместо сохранения всего продукта просто сохраните атрибут для продукта с помощью saveAttribute
// require magento core
require_once 'app/Mage.php';
// execute on admin store
Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
$products = Mage::getModel('catalog/product')->getCollection();
echo $products->getSelect();//this will give sql query just run your db.
foreach($products as $product)
{
$product->setBranding('kib');
$product->getResource()->saveAttribute($product, 'branding');
}
Еще одно решение без петель
$store_id = 0;
$product_ids = Mage::getModel('catalog/product')
->getCollection()
->getAllIds();//you can apply some filters also
Mage::getSingleton('catalog/product_action')->updateAttributes(
$product_ids,//array of ids
array('branding' => 'kib'),//you can add some other attributes also as key value pair
$store_id
);