Rename active_record_internal_metadatas to ar_internal_metadata

for those who already migrated to Rails 5.0.0 beta

activerecord/lib/active_record/internal_metadata.rb

@@ -14,6 +14,10 @@ module ActiveRecord
         "#{table_name_prefix}#{ActiveRecord::Base.internal_metadata_table_name}#{table_name_suffix}"
       end
 
+      def original_table_name
+        "#{table_name_prefix}active_record_internal_metadatas#{table_name_suffix}"
+      end
+
       def []=(key, value)
         first_or_initialize(key: key).update_attributes!(value: value)
       end
@@ -26,8 +30,17 @@ module ActiveRecord
         ActiveSupport::Deprecation.silence { connection.table_exists?(table_name) }
       end
 
+      def original_table_exists?
+        # This method will be removed in Rails 5.1
+        # Since it is only necessary when `active_record_internal_metadatas` could exist
+        ActiveSupport::Deprecation.silence { connection.table_exists?(original_table_name) }
+      end
+
       # Creates an internal metadata table with columns +key+ and +value+
       def create_table
+        if original_table_exists?
+          connection.rename_table(original_table_name, table_name)
+        end
         unless table_exists?
           key_options = connection.internal_string_options_for_primary_key
 

activerecord/test/cases/migration_test.rb

@@ -426,6 +426,21 @@ class MigrationTest < ActiveRecord::TestCase
     ENV["RACK_ENV"]  = original_rack_env
   end
 
+  def test_rename_internal_metadata_table
+    original_internal_metadata_table_name = ActiveRecord::Base.internal_metadata_table_name
+
+    ActiveRecord::Base.internal_metadata_table_name = "active_record_internal_metadatas"
+    Reminder.reset_table_name
+
+    ActiveRecord::Base.internal_metadata_table_name = original_internal_metadata_table_name
+    Reminder.reset_table_name
+
+    assert_equal "ar_internal_metadata", ActiveRecord::InternalMetadata.table_name
+  ensure
+    ActiveRecord::Base.internal_metadata_table_name = original_internal_metadata_table_name
+    Reminder.reset_table_name
+  end
+
   def test_proper_table_name_on_migration
     reminder_class = new_isolated_reminder_class
     migration = ActiveRecord::Migration.new