2 files changed, 15 insertions, 1 deletions
diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index ee9bc22384..1ca6349117 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,10 @@
 *SVN*
 
+* Added a differenciation between AssociationCollection#size and -length. Now AssociationCollection#size returns the size of the 
+  collection by executing a SELECT COUNT(*) query if the collection hasn't been loaded and calling collection.size if it has. If 
+  it's more likely than not that the collection does have a size larger than zero and you need to fetch that collection afterwards, 
+  it'll take one less SELECT query if you use length.
+
 * Added Base#attributes that returns a hash of all the attributes with their names as keys and clones of their objects as values #433 [atyp.de]
 
 * Fixed that foreign keys named the same as the association would cause stack overflow #437 [Eric Anderson]
diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index 6283f3dc28..ca2adaa9c9 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -70,12 +70,21 @@ module ActiveRecord
         @collection = []
       end
       
+      # Returns the size of the collection by executing a SELECT COUNT(*) query if the collection hasn't been loaded and
+      # calling collection.size if it has. If it's more likely than not that the collection does have a size larger than zero
+      # and you need to fetch that collection afterwards, it'll take one less SELECT query if you use length.
       def size
         if loaded? then @collection.size else count_records end
       end
       
+      # Returns the size of the collection by loading it and calling size on the array. If you want to use this method to check
+      # whether the collection is empty, use collection.length.zero? instead of collection.empty?
+      def length
+        load_collection.size
+      end
+      
       def empty?
-        size == 0
+        size.zero?
       end
       
       def uniq(collection = self)