Migrate notification setting from members table

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

db/migrate/20160328115649_migrate_new_notification_setting.rb

+# This migration will create one row of NotificationSetting for each Member row
+# It can take long time on big instances. Its unclear yet if this migration can be done online.
+# This comment should be updated by @dzaporozhets before 8.7 release. If not - please ask him to do so.
+class MigrateNewNotificationSetting < ActiveRecord::Migration
+  def up
+    timestamp = Time.now
+    execute "INSERT INTO notification_settings ( user_id, source_id, source_type, level, created_at, updated_at ) SELECT user_id, source_id, source_type, notification_level, '#{timestamp}', '#{timestamp}' FROM members"
+  end
+
+  def down
+    NotificationSetting.delete_all
+  end
+end

db/migrate/20160328121138_add_notification_setting_index.rb

+class AddNotificationSettingIndex < ActiveRecord::Migration
+  def change
+    add_index :notification_settings, :user_id
+    add_index :notification_settings, [:source_id, :source_type]
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160328112808) do
+ActiveRecord::Schema.define(version: 20160328121138) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -647,6 +647,9 @@ ActiveRecord::Schema.define(version: 20160328112808) do
     t.datetime "updated_at",  null: false
   end
 
+  add_index "notification_settings", ["source_id", "source_type"], name: "index_notification_settings_on_source_id_and_source_type", using: :btree
+  add_index "notification_settings", ["user_id"], name: "index_notification_settings_on_user_id", using: :btree
+
   create_table "oauth_access_grants", force: :cascade do |t|
     t.integer  "resource_owner_id", null: false
     t.integer  "application_id",    null: false