In migrations, how do I change the length of a string?

I want to do:
      t.column :title, :string, :length => 100
or
      t.column :title, :string, :size => 100

How do I do it?

Also, where is some documentation about migrations?
http://api.rubyonrails.com/classes/ActiveRecord/Migration.html
That doesn't tell me stuff I want to know!

Thanks!

Ben Lisbakken

:limit => 100