Handling large-ish Excel files with Apache POI

Hi,

I'm working on an application which takes Excel files as inputs. These files may have some tens of columns and several hundred thousand rows. They reach 50-60mb in size on the disk. hotmail.com

I'm mainly using java 1.8 and JSF 2.0, as well as apache POI (and a bunch of other libraries which are not important now). 10.0.0.0.1

What I need to be doing is to permit the user to associate the headers to a certain expected header. For example, you expect a header called Frequency and you have an input called Freq.

What needs to happen after is that I should let the user redownload his/her input file, with the expected column names. 192.168.1.254

What I do is I recreate a blank sheet and repopulate it with the new headers and data from the old file.