Only define attribute methods from schema cache

To define the attribute methods for a model, Active Record needs to know
the schema of the underlying table, which is usually achieved by making
a request to the database. This is undesirable behaviour while the app
is booting, for two reasons: it makes the boot process dependent on the
availability of the database, and it means every new process will make
one query for each table, which can cause issues for large applications.

However, if the application is using the schema cache dump feature, then
the schema cache already contains the necessary information, and we can
define the attribute methods without causing any extra database queries.

1 files changed, 4 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 392602bc0f..85c87227ff 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -283,6 +283,10 @@ module ActiveRecord
         TypeCaster::Map.new(self)
       end
 
+      def _internal? # :nodoc:
+        false
+      end
+
       private
 
         def cached_find_by_statement(key, &block)