Update database migrations to build the expected table structure from…

… the start

db/migrate/20140202020201_create_searches.rb

@@ -3,7 +3,7 @@ class CreateSearches < ActiveRecord::Migration
   def self.up
     create_table :searches do |t|
       t.text  :query_params
-      t.integer :user_id
+      t.integer :user_id, index: true, null: false
       t.string :user_type
 
       t.timestamps null: false

db/migrate/20140202020202_create_bookmarks.rb

@@ -2,9 +2,10 @@
 class CreateBookmarks < ActiveRecord::Migration
   def self.up
     create_table :bookmarks do |t|
-      t.integer :user_id, :null=>false
+      t.integer :user_id, index: true, null: false
       t.string :user_type
-      t.string :document_id
+      t.string :document_id, index: true
+      t.string :document_type
       t.string :title
       t.timestamps null: false
     end

db/migrate/20140320000000_add_polymorphic_type_to_bookmarks.rb

@@ -1,8 +1,10 @@
 # frozen_string_literal: true
 class AddPolymorphicTypeToBookmarks < ActiveRecord::Migration
   def change
-    add_column(:bookmarks, :document_type, :string)
+    commit_db_transaction
+
+    add_column(:bookmarks, :document_type, :string) unless Bookmarks.connection.column_exists? :bookmarks, :user_id
 
-    add_index :bookmarks, :user_id
+    add_index :bookmarks, :user_id unless Bookmarks.connection.index_exists? :bookmarks, :user_id
   end
 end