Adding notifications column

db/migrate/20161119211120_create_notifications.rb

@@ -9,5 +9,6 @@ class CreateNotifications < ActiveRecord::Migration[5.0]
     end
 
     add_index :notifications, :account_id
+    add_index :notifications, [:account_id, :activity_id, :activity_type], unique: true, name: 'account_activity'
   end
 end

db/schema.rb

@@ -102,6 +102,7 @@ ActiveRecord::Schema.define(version: 20161119211120) do
     t.string   "activity_type"
     t.datetime "created_at",    null: false
     t.datetime "updated_at",    null: false
+    t.index ["account_id", "activity_id", "activity_type"], name: "account_activity", unique: true, using: :btree
     t.index ["account_id"], name: "index_notifications_on_account_id", using: :btree
   end