php - MongoDB - 为什么我应该使用游标而不是 iterator_to_array(在 PHP 中)

Question

mongo 类的 PHP 文档说 using a cursor而不是 iterator_to_array 更好。

为什么？我将从中获得什么好处/灵 active ？

Answer 1

使用 iterator_to_array() 使您的驱动程序一次将所有结果加载到内存中，并且您很容易耗尽内存。使用延迟加载的游标不会出现这种情况!

直接来自链接docs :

<?php

$cursor = $collection->find();
var_dump(iterator_to_array($cursor));

?>

...

Suppose that, in the example above, $collection was a 50GB collection. We certainly wouldn't want to load that into memory all at once, which is what a cursor is for: allowing the client to access the collection in dribs and drabs.