优化foreach数千项

Question

I'm running the code below over a set of 25,000 results. I need to optimize it because i'm hitting the memory limit.

$oldproducts = Oldproduct::model()->findAll(); /*(here i have 25,000 results)*/

foreach($oldproducts as $oldproduct) :
    $criteria = new CDbCriteria;
    $criteria->compare('`someid`', $oldproduct->someid);
    $finds = Newproduct::model()->findAll($criteria);

    if (empty($finds)) {
        $new = new Newproduct;
        $new->someid = $oldproduct->someid;
        $new->save();
    } else {
        foreach($finds as $find) :
            if ($find->price != $oldproduct->price) {
                $find->attributes=array('price' => $oldproduct->price);
                $find->save();
            }
        endforeach;
    }
endforeach;

Code compares rows of two tables by someid. If it find coincidence it updates price column, if not creates a new record.

Answer 1

Use CDataProviderIterator which:

... allows iteration over large data sets without holding the entire set in memory.

You first have to pass a CDataProvider instance to it:

$dataProvider = new CActiveDataProvider("Oldproduct");
$iterator = new CDataProviderIterator($dataProvider);
foreach($iterator as $item) {
    // do stuff
}