使用PHP打开HUGE XML文件

I've a little problem.

I've a file that is around 53GB. I need to open the file with PHP and import the lines to my database.

My problem is: Does anyone have some tips how to open files on that size?

I've tried some different solutions with fopen and some DOM functions, but I only get "XMLReader::XML(): Empty string supplied as input in" but the file is 53GB, so I know that there is something inside the file.

Hope someone can help