<?php
$a = $b = $c = $d = $e = $f = $g = $h = array("my" => "document");
$obj = array("document" => "my");

$bulk = new MongoDB\Driver\BulkWrite(true);
$bulk->insert($a);
$bulk->insert($b);
$bulk->update($c, $obj);
$bulk->update($d, $obj);
$bulk->delete($e);
$bulk->delete($f);
$bulk->update($g, $obj);
$bulk->delete($h);
var_dump(count($bulk));
?>

<?php
$a = $b = $c = $d = $e = $f = $g = $h = array("my" => "document");
$obj = array("document" => "my");

$bulk = new MongoDB\Driver\BulkWrite(false);
$bulk->insert($a);
$bulk->insert($b);
$bulk->update($c, $obj);
$bulk->update($d, $obj);
$bulk->delete($e);
$bulk->delete($f);
$bulk->update($g, $obj);
$bulk->delete($h);
var_dump(count($bulk));
?>