index for commit_id. Schema rebuiled. Non rollback migration exception added

db/migrate/20121218164840_move_noteable_commit_to_own_field.rb

@@ -15,7 +15,6 @@ class MoveNoteableCommitToOwnField < ActiveRecord::Migration
   end
 
   def down
-    remove_column :notes, :commit_id
-    remove_column :notes, :new_noteable_id
+    raise ActiveRecord::IrreversibleMigration
   end
 end

db/migrate/20121219095402_indices_for_notes.rb

@@ -0,0 +1,6 @@
+class IndicesForNotes < ActiveRecord::Migration
+  def change
+    add_index :notes, :commit_id
+    add_index :notes, [:project_id, :noteable_type]
+  end
+end