PDO MySQL fetchAll()是否在结果中使用了两倍的必要内存? [英] PDO MySQL fetchAll() using double the necessary memory in result?

问题描述

当我将->fetchAll()与PDO一起使用时，当我执行print_r()时，结果数组如下所示:

When I use ->fetchAll() with PDO, the resulting array looks like this when I do a print_r():

Array
(
    [0] => Array
        (
            [week] => 2006-03-05
            [0] => 2006-03-05
            [ath] => 112.89166667
            [1] => 112.89166667
        )

    [1] => Array
        (
            [week] => 2006-03-12
            [0] => 2006-03-12
            [ath] => 260.04527778
            [1] => 260.04527778
        )

    [2] => Array
        (
            [week] => 2006-03-19
            [0] => 2006-03-19
            [ath] => 219.23472222
            [1] => 219.23472222
        )

等，等等.

结果值是否两次存储在内存中?一个在数字数组索引下，例如0和1，另一个在其命名索引下，例如week或ath?

Are the resulting values stored twice in memory? One under a numerical array index like 0 and 1, and the other under its named index, such as week or ath?

我主要只是好奇.我不认为这会真正影响我的程序.谢谢.

I am mainly just curious. I don't expect this to really impact my program significantly. Thanks.

推荐答案

结果值是否两次存储在内存中?

Are the resulting values stored twice in memory?

是的.请参见手册:

PDO :: FETCH_BOTH(默认值):返回一个在结果集中返回的同时由列名和0索引列号索引的数组

PDO::FETCH_BOTH (default): returns an array indexed by both column name and 0-indexed column number as returned in your result set

使用可选的$fetch_style参数来更改fetchAll()的行为方式.

Use the optional $fetch_style parameter to change the way fetchAll() behaves.

$result = $sth->fetchAll(PDO::FETCH_ASSOC);

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