为什么“允许的内存大小用尽"?

问题描述

我正在编写批处理脚本，并出现Allowed memory size of 134217728 bytes exhausted错误.

I am writing a batch script and get a Allowed memory size of 134217728 bytes exhausted error.

我不明白为什么内存已满.我尝试取消设置$row变量，但这并没有改变任何事情.这是我的代码:

I don't understand why the memory is filling up. I tried unsetting the $row variable, but that didn't change a thing. Here is my code:

// ... (sql connection)
$result = mysql_query("SELECT * FROM large_table");

while ($row = mysql_fetch_array($result)) {
    echo $row['id'] . PHP_EOL;
    unset($row);
}

(简化代码)

为什么内存已满，如何避免呢?

Why does the memory fill up, and how can I avoid it?

注意:这是一个批处理脚本.我必须处理这样的数据(遍历一百万行)，这是正常的.

Note: this is a batch script. This is normal that I have to handle data like that (go through 1 million lines).

更新:内存不足发生在第40万行附近，所以这一定是在循环中吗?我希望尽可能避免实施分页.

推荐答案

尝试使用 http://www.php.net/manual/zh/function.mysql-unbuffered-query.php (mysql_unbuffered_query())，以防止将整个表加载到内存中，但仍避免分页

Try using http://www.php.net/manual/en/function.mysql-unbuffered-query.php (mysql_unbuffered_query()) to prevent the whole table being loaded into memory, but still avoiding pagination.

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