Add a quick note about :select and eagerly included associations. [Rick]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4363 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 4 insertions, 1 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index c501af6f44..76762fc3e4 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Add a quick note about :select and eagerly included associations. [Rick]
+
 * Add docs for the :as option in has_one associations.  Closes #5144 [cdcarter@gmail.com]
 
 * Fixed that has_many collections shouldn't load the entire association to do build or create [DHH]
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 3d207aab61..ad28407e57 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -348,7 +348,8 @@ module ActiveRecord
     #
     # Also have in mind that since the eager loading is pulling from multiple tables, you'll have to disambiguate any column references
     # in both conditions and orders. So :order => "posts.id DESC" will work while :order => "id DESC" will not. This may require that
-    # you alter the :order and :conditions on the association definitions themselves.
+    # you alter the :order and :conditions on the association definitions themselves.  Because eager loading generates the SELECT statement too,
+    # the :select option is ignored.
     #
     # It's currently not possible to use eager loading on multiple associations from the same table. Eager loading will not pull
     # additional attributes on join tables, so "rich associations" with has_and_belongs_to_many is not a good fit for eager loading.