Performance: Better query for ASSOCIATION_ids. Select only ids if the association hasn't been loaded.

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 3ca93db10f..62cc414555 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1304,7 +1304,11 @@ module ActiveRecord
           end
 
           define_method("#{reflection.name.to_s.singularize}_ids") do
-            send(reflection.name).map { |record| record.id }
+            if send(reflection.name).loaded?
+              send(reflection.name).map(&:id)
+            else
+              send(reflection.name).all(:select => "#{reflection.quoted_table_name}.id").map(&:id)
+            end
           end
         end