<?php

$time = microtime(true);

$mem = memory_get_usage();

$dbh = new PDO('mysql:dbname=DBNAME;host=localhost', 'USERNAME', 'PASSWORD');
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$stmt = $dbh->prepare('SELECT * FROM EVENTS LIMIT 400000');
$stmt->execute();

if ($argv[1] == "fetch") {
  $data = [];
  while ($row = $stmt->fetch()) {
    $data[] = $row;
  }
} elseif ($argv[1] == "fetchall") {
  $data = $stmt->fetchAll();
  $i = 0;
  foreach ($data as $r) {
    $i++;
  }
}

print_r(array('memory' => (memory_get_usage() - $mem) / (1024 * 1024), 'seconds' => microtime(TRUE) - $time));



/** Results

$ php test.php fetch
Array
(
    [memory] => 1613.3364639282
    [seconds] => 5.0663459300995
)

$ php test.php fetchall
Array
(
    [memory] => 1613.3367156982
    [seconds] => 5.068785905838
)

**/