magento - Get Number of Orders per Product -

i'm trying build array of orders => products can use in reporting/updating attributes. format i'm going is:

//$orders[<number of orders>] = <array of product ids many orders> $orders = array(     1 => array(1, 2, 3),     2 => array(4, 5)     //etc ); 

so far best can is

$productcollection = mage::getmodel('catalog/product')     ->addattributetoselect("sku")     ->getcollection();  $orders = array();  foreach ($productcollection $product) {      $ordered = mage::getresourcemodel('reports/product_collection')         ->addorderedqty()         ->addattributetofilter('sku', $product->getsku())         ->setorder('ordered_qty', 'desc')         ->getfirstitem();      $qtyordered = $ordered->getorderedqty();     $total = $this->_counter - (int)(!$ordered ? 0 : $qtyordered);      if (!is_array($orders[$total])) {          $orders[$total] = array();     }      $orders[$total][] = $product->getid(); } 

but using lot of resources, loading entire product collection.

i think can using

$ordered = mage::getresourcemodel('reports/product_collection')     ->addorderedqty(); 

but i'm having trouble returning/iterating through results. how extract information i'm looking for?

this should better.

$orderitems = mage::getresourcemodel('sales/order_item_collection');  $result = array(); foreach ($orderitems $item) {     $result[$item->getorderid()][] = $item->getproductid(); }  print_r($result); 

note: take care hidden order item (ex: simple, configurable product)