1class CreateActivitiesTable < ActiveRecord::Migration
 2  def change
 3    create_table :activities do |t|
 4      t.integer :subject_id, null: false
 5      t.string :subject_type, null: false
 6      t.integer :user_id, null: false
 7      t.timestamps null: false
 8    end
 9
10    add_index :activities, :subject_id
11    add_index :activities, :subject_type
12    add_index :activities, :user_id
13  end
14end