Optimizer hints should be applied on Top level query as much as possible

I've experienced this issue in our app, some hints only works on Top
level query (e.g. `MAX_EXECUTION_TIME`).

2 files changed, 13 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 4f9ddf302e..0384023a17 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -416,16 +416,17 @@ module ActiveRecord
 
       def build_count_subquery(relation, column_name, distinct)
         if column_name == :all
+          column_alias = Arel.star
           relation.select_values = [ Arel.sql(FinderMethods::ONE_AS_ONE) ] unless distinct
         else
           column_alias = Arel.sql("count_column")
           relation.select_values = [ aggregate_column(column_name).as(column_alias) ]
         end
 
-        subquery = relation.arel.as(Arel.sql("subquery_for_count"))
-        select_value = operation_over_aggregate_column(column_alias || Arel.star, "count", false)
+        subquery_alias = Arel.sql("subquery_for_count")
+        select_value = operation_over_aggregate_column(column_alias, "count", false)
 
-        Arel::SelectManager.new(subquery).project(select_value)
+        relation.build_subquery(subquery_alias, select_value)
       end
   end
 end
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index b0535cfff5..5f728f2263 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -992,6 +992,15 @@ module ActiveRecord
       @arel ||= build_arel(aliases)
     end
 
+    protected
+      def build_subquery(subquery_alias, select_value) # :nodoc:
+        subquery = except(:optimizer_hints).arel.as(subquery_alias)
+
+        Arel::SelectManager.new(subquery).project(select_value).tap do |arel|
+          arel.optimizer_hints(*optimizer_hints_values) unless optimizer_hints_values.empty?
+        end
+      end
+
     private
       # Returns a relation value with a given name
       def get_value(name)