Quick question: making tables without id fields; migrations

I just started a tagging system for my site and I was getting funky
errors when adding tags. I looked at the the data in the tables and
realized that rails was only allowing me to save each tag once! Which
meant that if i saved a tag for post 1, then i couldn’t associate that
tag with any other post.

Some head-scratching and cursing later, I remembered that join tables in
HABTM relationships can’t have id fields. Awesome! I can fix it.

Tha only problem is I don’t know how I would do that (make a table with
no id column) using migrations. Anybody know?

Never mind! Got it!

:id => false