avoid calling to_sql when we can

activerecord/lib/active_record/relation/calculations.rb

@@ -208,12 +208,12 @@ def execute_grouped_calculation(operation, column_name) #:nodoc:
       aggregate_alias = column_alias_for(operation, column_name)
 
       select_statement = if operation == 'count' && column_name == :all
-        "COUNT(*) AS count_all"
+        ["COUNT(*) AS count_all"]
       else
-        Arel::Attribute.new(@klass.unscoped.table, column_name).send(operation).as(aggregate_alias).to_sql
+        [Arel::Attribute.new(@klass.unscoped.table, column_name).send(operation).as(aggregate_alias)]
       end
 
-      select_statement <<  ", #{group_field} AS #{group_alias}"
+      select_statement <<  "#{group_field} AS #{group_alias}"
 
       relation = except(:group).select(select_statement).group(group)
 

activerecord/lib/active_record/relation/query_methods.rb

@@ -36,7 +36,7 @@ def select(value = Proc.new)
         to_a.select {|*block_args| value.call(*block_args) }
       else
         relation = clone
-        relation.select_values += [value]
+        relation.select_values += Array.wrap(value)
         relation
       end
     end