[Docs] Query::toIterable with fetch-join

[JoniJnm]

Hi, the documentation about Query::toIterable says:

Iterating results is not possible with queries that fetch-join a collection-valued association. The nature of such SQL result sets is not suitable for incremental hydration.

What does this mean exactly? The second argument accepts a $hydrationMode = self::HYDRATE_OBJECT so don't understand the message.

orm/lib/Doctrine/ORM/Query.php

Lines 738 to 743 in 5577d51

	public function toIterable(iterable $parameters = [], $hydrationMode = self::HYDRATE_OBJECT): iterable
	{
	$this->setHint(self::HINT_INTERNAL_ITERATION, true);
	return parent::toIterable($parameters, $hydrationMode);
	}