读取大文件时出现内存不足错误 - Out of memory error when reading a large file

Out of memory error when reading a large file

我有一个大的csv，我想解析并插入到我的数据库中。这里是PHP:

$target = '../uploads/'.$f;
$handle = fopen($target, "r");
$data = fgetcsv($handle, 0, ",");
$rows = array();
while ($data !== FALSE) {
    $rows[] =  $data;
}
fclose($handle);
if (count($rows)) {
             foreach ($rows as $key => $value) {
                  echo $value;
              }
          }

每次我试图运行我的脚本，我得到这个错误:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 35 bytes)

有什么办法吗?

我认为这部分是错误的:

$data = fgetcsv($handle, 0, ",");
$rows = array();
while ($data !== FALSE) {
    $rows[] =  $data;
}

对fgetcsv的一次调用读取$handle的一行。您需要将fgetcsv放入循环条件:

$handle = fopen($target, "r");
$data = fgetcsv($handle, 0, ",");
while (($row = fgetcsv($handle, 0, ",")) !== FALSE) {
    // Example insert - obviously use prepared statements/escaping/another DAL
    $db->query("INSERT INTO tbl (columns..) VALUES ({$row[0]}, {$row[1]} ... )");
}

使用mysqlimport代替

虽然你可以用PHP解析和构建查询，但如果让MySQL直接处理，你会得到更好的性能。你的数据库会感谢你的。

<?php
exec("mysqlimport mysqlimport [options] db_name textfile1");
?>

来源:

http://www.php.net/manual/en/function.exec.php
http://dev.mysql.com/doc/refman/5.0/en/mysqlimport.html

您不需要在处理之前将文件中的所有csv数据读入内存。

相反，创建一个while循环，每次从文件中读取一行。每次从文件中读取时，都应该向数据库中插入一行。

或者一次读取几行并插入几行。

例子:

   $i = 0; 
   while (($data = fgetcsv($handle, 0, ",") !== FALSE) {
        $rows[] = $data;
        $i++;
        // insert 100 rows at one time.
        if ($i % 100 === 0) {
            //insert these rows to db
            insert_to_db($rows);
            //then reset $rows
            $rows = array();
        }
    }
    insert_to_db($rows);

使用标准的MySQL LOAD DATA INFILE语句逃避通过PHP读取/解析/插入数据:

 function import_csv( $table, $afields, $filename, $delim = ',', $enclosed = '"', $escaped = '''',  $lineend = '''r''n', $hasheader = FALSE) {      
    if ( $hasheader ) $ignore = "IGNORE 1 LINES ";
    else $ignore = "";
    $q_import = 
        "LOAD DATA INFILE '" . $_SERVER['DOCUMENT_ROOT'] . $filename . "' INTO TABLE " . $table . " " .
        "FIELDS TERMINATED BY '" . $delim . "' ENCLOSED BY '" . $enclosed . "' " .
        "    ESCAPED BY '" . $escaped . "' " .
        "LINES TERMINATED BY '" . $lineend . "' " . $ignore . "(" . implode(',', $afields) . ")"
    ;
    return mysql_query($q_import);
}

在这种情况下，您不需要在PHP中打开/读取CSV文件，MySQL将自行处理数据导入