千篇一律的foreach优化

2021-12-26 00:00:00 optimization memory foreach php yii

我正在对一组 25,000 结果运行下面的代码.我需要优化它，因为我达到了内存限制.

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;

代码通过someid比较两个表的行.如果发现巧合，它会更新 price 列，否则会创建一个新记录.

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

推荐答案

使用 CDataProviderIterator 其中:

Use CDataProviderIterator which:

... 允许对大型数据集进行迭代，而无需将整个数据集保存在内存中.

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

您首先必须将 CDataProvider 实例传递给它:

You first have to pass a CDataProvider instance to it:

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

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