I'd like to mirror just the category structure of the English Wikipedia, and I'm wondering which of the dump files I need to start with.

I don't need the page content, just the page names, and only for the most current revision.  I need the categories and category members, and I'd like to exclude hidden categories.  I also need to distinguish redirects, because I don't want to treat them as separate pages.  As much as possible I'd like to work with SQL files, but I can crunch through XML if necessary.

So which files do I need to download?  I may also need some help in understanding the schemas.

Thanks,

Robert