几乎没有200k随机记录的基准。与预期的一样，fetchAll方法更快，但需要更多的内存。
Result :fetchAll : 0.35965991020203s, 100249408bfetch : 0.39197015762329s, 440b
使用的基准代码：
<?php// First benchmark : speed$dbh = new PDO('mysql:dbname=testage;dbhost=localhost', 'root', '');$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);$sql = 'SELECt * FROM test_table WHERe 1';$stmt = $dbh->query($sql);$data = array();$start_all = microtime(true);$data = $stmt->fetchAll();$end_all = microtime(true);$stmt = $dbh->query($sql);$data = array();$start_one = microtime(true);while($data = $stmt->fetch()){}$end_one = microtime(true);// Second benchmark : memory usage$stmt = $dbh->query($sql);$data = array();$memory_start_all = memory_get_usage();$data = $stmt->fetchAll();$memory_end_all = memory_get_usage();$stmt = $dbh->query($sql);$data = array();$memory_end_one = 0;$memory_start_one = memory_get_usage();while($data = $stmt->fetch()){ $memory_end_one = max($memory_end_one, memory_get_usage());}echo 'Result : <br/>fetchAll : ' . ($end_all - $start_all) . 's, ' . ($memory_end_all - $memory_start_all) . 'b<br/>fetch : ' . ($end_one - $start_one) . 's, ' . ($memory_end_one - $memory_start_one) . 'b<br/>';
