The Problem
Your doing migrations for a database and you must specify a column with a database specific type. You've checked all of the ActiveRecord migration options and none fit the bill.
An Example Situation
You must specify bigint or int2vector or polygon for a PostgreSQL database.
The Solution
Here's what you can do to solve the problem of ActiveRecord migration limitations for column types:
create_table :special_table do |t| t.column :name, :string, :limit => 100 t.column :some_foreign_key, :integer t.columns << 'some_big_integer bigint' t.columns << 'a_polygon polygon' end