How do I force a full index before the supplemental index is built?

I thought my computer was reindexing from scratch after the big download, but then I did a search and saw the New Resources section.  I'd really like it to index everything, but I can't--at least until it is finished building the supplemental index, which is probably going to be bigger than the main index.  Is there a file I can delete to force a complete reindexing?