Get WordPress posts incremently to save on PHP memory usage

gistfile1.php

// memory friendly alternative to get_posts( array( 'posts_per_page' => '-1' ) );

$product_page = 1;
$product_per_page = 10;
$product_query = new WP_Query( array(
	'posts_per_page' => $product_per_page,
	'paged'          => $product_page,
	'post_type'      => array( 'product', 'product_variation' ),
) );
$product_ids = array();
while($product_query->have_posts() ) {
	$product_result = $product_query->next_post();
	if(!$product_result){
		// get the next lot of results.
		$product_page++;
		$product_query = new WP_Query( array(
			'posts_per_page' => $product_per_page,
			'paged'          => $product_page,
			'post_type'      => array( 'product', 'product_variation' ),
		) );
	}else{
		$product_ids[] = $product_result->ID;
	}
}
print_r($product_ids);