在Perl中，如何解析一个太大而无法装入可用内存的XML文件?

I have a very large XML file (If you care, it's an AIXM file from EAD, but that's not important). In order to figure out how it is used, I want to write a simple script that goes through and for every node, record what subnodes occur below it and how many times, so I can see which nodes contain I have a very large XML file (If you care, it's