change transactional primary key to custom ID for better portability

db/migrate/20170404034234_create_bookings.rb

@@ -1,6 +1,8 @@
 class CreateBookings < ActiveRecord::Migration[5.0]
   def change
-    create_table :bookings do |t|
+    create_table :bookings, :id => false, :primary_key => :booking_id do |t|
+      t.string :booking_id, :limit => 16, :null => false, :index => true, :unique => true #custom primary key - to ensure consistence for cloud syncing
+
       t.references :dining_facility, foreign_key: true
       t.string :type, :null => false, :default => "Table"
       t.datetime :checkin_at, :null => false
@@ -10,7 +12,8 @@ class CreateBookings < ActiveRecord::Migration[5.0]
       t.datetime :reserved_at
       t.string :reserved_by
       t.string :booking_status, :null => false, :default => "new"
-      t.references :sale, foreign_key: true
+      t.string :sale_id, foreign_key: true, :limit => 16
+      t.string :customer_id, foreign_key: true, :limit => 16
 
       t.timestamps
     end