cacheable_default_scope.rb

diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index d957bd1..60d3002 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -130,7 +130,7 @@ module ActiveRecord
         return super if ids.first.kind_of?(Symbol)
         return super if block_given? ||
                         primary_key.nil? ||
-                        default_scopes.any? ||
+                        !default_scopes.all?(&:cacheable?) ||
                         current_scope ||
                         columns_hash.include?(inheritance_column) ||
                         ids.first.kind_of?(Array)
@@ -161,7 +161,7 @@ module ActiveRecord
 
       def find_by(*args)
         return super if current_scope || !(Hash === args.first) || reflect_on_all_aggregations.any?
-        return super if default_scopes.any?
+        return super unless default_scopes.all?(&:cacheable?)
 
         hash = args.first
 
diff --git a/activerecord/lib/active_record/scoping/default.rb b/activerecord/lib/active_record/scoping/default.rb
index 18190cb..27a540f 100644
--- a/activerecord/lib/active_record/scoping/default.rb
+++ b/activerecord/lib/active_record/scoping/default.rb
@@ -82,6 +82,9 @@ module ActiveRecord
         #   end
         def default_scope(scope = nil)
           scope = Proc.new if block_given?
+          def scope.cacheable?
+            false
+          end
 
           if scope.is_a?(Relation) || !scope.respond_to?(:call)
             raise ArgumentError,
@@ -94,6 +97,15 @@ module ActiveRecord
           self.default_scopes += [scope]
         end
 
+        def cached_default_scope(scope = nil)
+          scope = Proc.new if block_given?
+          def scope.cacheable?
+            true
+          end
+
+          self.default_scopes += [scope]
+        end
+
         def build_default_scope(base_rel = relation) # :nodoc:
           if !Base.is_a?(method(:default_scope).owner)
             # The user has defined their own default scope method, so call that