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PDO 读取语句之间是否存在性能差异？

php pdo fetch
2022-08-30 16:31:18

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/* Exercise PDOStatement::fetch styles */
print("PDO::FETCH_ASSOC: ");
print("Return next row as an array indexed by column name\n");
$result = $sth->fetch(PDO::FETCH_ASSOC);
print_r($result);
print("\n");

print("PDO::FETCH_BOTH: ");
print("Return next row as an array indexed by both column name and number\n");
$result = $sth->fetch(PDO::FETCH_BOTH);
print_r($result);
print("\n");

print("PDO::FETCH_LAZY: ");
print("Return next row as an anonymous object with column names as properties\n");
$result = $sth->fetch(PDO::FETCH_LAZY);
print_r($result);
print("\n");

print("PDO::FETCH_OBJ: ");
print("Return next row as an anonymous object with column names as properties\n");
$result = $sth->fetch(PDO::FETCH_OBJ);
print $result->NAME;
print("\n");

好吧，默认值是FETCH BOTH，我想知道当我要获取大量数据时，FETCH ASSOC是否更快;还是他们是一样的？

谢谢


答案 1

我想知道这个问题的答案，所以我写了一个快速的基准测试脚本。

我建议您在自己的服务器上运行此基准测试，但是，这是我的设置中的典型结果，用于单行结果：

  1. PDO：：FETCH_ASSOC - 936 ms
  2. PDO：：FETCH_BOTH - 948 ms
  3. PDO：：FETCH_NUM - 1，184 ms
  4. PDO：：FETCH_OBJ - 1，272 ms
  5. PDO：：FETCH_LAZY - 1，276 ms

对于大型数据集，这些结果是典型的：

  1. PDO：：FETCH_LAZY - 5，490 ms
  2. PDO：：FETCH_NUM - 8，818 ms
  3. PDO：：FETCH_ASSOC- 10，220 ms
  4. PDO：：FETCH_BOTH - 11，359 ms
  5. PDO：：FETCH_OBJ - 14，027 ms

请参阅 git 中心上的注释，获取所有行确实会更改测试。


答案 2

在另一个答案中发布的基准测试脚本正在将 prepare（） 和 execute（） 计数到时间，所以我编写了一个仅用于测试获取时间的脚本。我有MySQL数据库，大约有100000行真实数据。LongRow 包含 TEXT 列（每行约 4kB 的数据）。ShortRow 是（每行 30 个字节）。FETCH_INTO使用具有所有列属性的预定义类。PHP 版本 5.4.MySQL 5.5.35.这里缺少一件事：一些运行的平均值。

Array
(
    [Items: 10] => Array
        (
            [ShortRow] => Array
                (
                    [FETCH_INTO] => 0.0001068115234375
                    [FETCH_OBJECT] => 0.00013899803161621
                    [FETCH_COLUMN (STR8)] => 6.0081481933594E-5
                    [FETCH_COLUMN (INT)] => 5.8174133300781E-5
                    [FETCH_NUM] => 9.2029571533203E-5
                    [FETCH_ASSOC] => 9.8943710327148E-5
                    [FETCH_BOTH] => 0.00011897087097168
                    [FETCH_LAZY] => 6.3180923461914E-5
                )

            [LongRow] => Array
                (
                    [FETCH_INTO] => 0.00012779235839844
                    [FETCH_OBJECT] => 0.00016498565673828
                    [FETCH_COLUMN (TEXT)] => 4.9829483032227E-5
                    [FETCH_COLUMN (INT)] => 4.3153762817383E-5
                    [FETCH_NUM] => 0.00010180473327637
                    [FETCH_ASSOC] => 0.00010895729064941
                    [FETCH_BOTH] => 0.00013399124145508
                    [FETCH_LAZY] => 4.3869018554688E-5
                )

        )

    [Items: 100] => Array
        (
            [ShortRow] => Array
                (
                    [FETCH_INTO] => 0.00081610679626465
                    [FETCH_OBJECT] => 0.0011789798736572
                    [FETCH_COLUMN (STR8)] => 0.00040292739868164
                    [FETCH_COLUMN (INT)] => 0.00041294097900391
                    [FETCH_NUM] => 0.00067806243896484
                    [FETCH_ASSOC] => 0.00076103210449219
                    [FETCH_BOTH] => 0.00092482566833496
                    [FETCH_LAZY] => 0.00043201446533203
                )

            [LongRow] => Array
                (
                    [FETCH_INTO] => 0.0010471343994141
                    [FETCH_OBJECT] => 0.0013670921325684
                    [FETCH_COLUMN (TEXT)] => 0.00037693977355957
                    [FETCH_COLUMN (INT)] => 0.00030612945556641
                    [FETCH_NUM] => 0.00079894065856934
                    [FETCH_ASSOC] => 0.00094914436340332
                    [FETCH_BOTH] => 0.0011270046234131
                    [FETCH_LAZY] => 0.00031089782714844
                )

        )

    [Items: 1000] => Array
        (
            [ShortRow] => Array
                (
                    [FETCH_INTO] => 0.0082287788391113
                    [FETCH_OBJECT] => 0.0099248886108398
                    [FETCH_COLUMN (STR8)] => 0.0037147998809814
                    [FETCH_COLUMN (INT)] => 0.0038070678710938
                    [FETCH_NUM] => 0.006443977355957
                    [FETCH_ASSOC] => 0.0070838928222656
                    [FETCH_BOTH] => 0.008652925491333
                    [FETCH_LAZY] => 0.0039060115814209
                )

            [LongRow] => Array
                (
                    [FETCH_INTO] => 0.0092909336090088
                    [FETCH_OBJECT] => 0.011745929718018
                    [FETCH_COLUMN (TEXT)] => 0.0031650066375732
                    [FETCH_COLUMN (INT)] => 0.0025970935821533
                    [FETCH_NUM] => 0.0068809986114502
                    [FETCH_ASSOC] => 0.0087978839874268
                    [FETCH_BOTH] => 0.010183811187744
                    [FETCH_LAZY] => 0.0026650428771973
                )

        )

    [Items: 10000] => Array
        (
            [ShortRow] => Array
                (
                    [FETCH_INTO] => 0.067224025726318
                    [FETCH_OBJECT] => 0.086459159851074
                    [FETCH_COLUMN (STR8)] => 0.03191089630127
                    [FETCH_COLUMN (INT)] => 0.031462907791138
                    [FETCH_NUM] => 0.047988891601562
                    [FETCH_ASSOC] => 0.05333399772644
                    [FETCH_BOTH] => 0.065713882446289
                    [FETCH_LAZY] => 0.028834819793701
                )

            [LongRow] => Array
                (
                    [FETCH_INTO] => 0.12389183044434
                    [FETCH_OBJECT] => 0.15812706947327
                    [FETCH_COLUMN (TEXT)] => 0.03816294670105
                    [FETCH_COLUMN (INT)] => 0.035914897918701
                    [FETCH_NUM] => 0.1117901802063
                    [FETCH_ASSOC] => 0.10923099517822
                    [FETCH_BOTH] => 0.12394094467163
                    [FETCH_LAZY] => 0.030914068222046
                )

        )

)

这里也是一个代码：



    //Code is missing connect to DB
    header('Content-Type: text/plain');
    class testModel1 {
        public $id;
        public $invoice;
        public $transaction;
        public $creditedInvoice;
        public $amount;
        public $payment_type;
        public $currency;
        public $created;
        public $timestamp;
    }

    class testModel2 {
        public $id;
        public $cid;
        public $c_amount;
        public $object;
        public $person;
        public $date;
        public $type;
        public $invoice_type;
        public $version;
        public $templateInvoice;
        public $account;
        public $variable_symbol;
        public $number;
        public $accounting_year;
        public $amount;
        public $currency;
        public $comment;
        public $data;   //is a text column (avg size about 4kB)
        public $created;
        public $modified;
        public $timestamp;
    }
    $items = array(10,100,1000,10000);
    foreach($items as $item) {
        $ivStmt = $pdo->prepare("SELECT * FROM `invoices_paying` LIMIT $item");
        $ivStmt->execute(array('items'=>$item));
        $out = array();
        $testModel1 = new testModel1();
        $ivStmt->setFetchMode(PDO::FETCH_INTO, $testModel1);
        $start = microtime(true); 
        while($id = $ivStmt->fetch()) {
        }
        $end = microtime(true);
        $out['FETCH_INTO'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetchObject()) {
        }
        $end = microtime(true);
        $out['FETCH_OBJECT'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetchColumn(5)) {
        }
        $end = microtime(true);
        $out['FETCH_COLUMN (STR8)'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetchColumn(0)) {
        }
        $end = microtime(true);
        $out['FETCH_COLUMN (INT)'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_NUM)) {
        }
        $end = microtime(true);
        $out['FETCH_NUM'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_ASSOC)) {
        }
        $end = microtime(true);
        $out['FETCH_ASSOC'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_BOTH)) {
        }
        $end = microtime(true);
        $out['FETCH_BOTH'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_LAZY)) {
        }
        $end = microtime(true);
        $out['FETCH_LAZY'] = $end-$start;

        $table['Items: '.$item]['ShortRow'] = $out;
    }
    foreach($items as $item) {
        $ivStmt = $pdo->prepare("SELECT * FROM `invoices` LIMIT $item");
        $ivStmt->execute(array('items'=>$item));
        $out = array();
        $testModel2 = new testModel2();
        $ivStmt->setFetchMode(PDO::FETCH_INTO, $testModel2);
        $start = microtime(true); 
        while($id = $ivStmt->fetch()) {
        }
        $end = microtime(true);
        $out['FETCH_INTO'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetchObject()) {
        }
        $end = microtime(true);
        $out['FETCH_OBJECT'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetchColumn(17)) {
        }
        $end = microtime(true);
        $out['FETCH_COLUMN (TEXT)'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetchColumn(0)) {
        }
        $end = microtime(true);
        $out['FETCH_COLUMN (INT)'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_NUM)) {
        }
        $end = microtime(true);
        $out['FETCH_NUM'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_ASSOC)) {
        }
        $end = microtime(true);
        $out['FETCH_ASSOC'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_BOTH)) {
        }
        $end = microtime(true);
        $out['FETCH_BOTH'] = $end-$start;

        $ivStmt->execute(array('items'=>$item));
        $start = microtime(true); 
        while($id = $ivStmt->fetch(PDO::FETCH_LAZY)) {
        }
        $end = microtime(true);
        $out['FETCH_LAZY'] = $end-$start;

        $table['Items: '.$item]['LongRow'] = $out;
    }
    print_r($table);

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