5 files changed, 27 insertions, 12 deletions
diff --git a/lib/arel/relations/compound.rb b/lib/arel/relations/compound.rb
index ca192a6e8a..94616ff14f 100644
--- a/lib/arel/relations/compound.rb
+++ b/lib/arel/relations/compound.rb
@@ -2,7 +2,7 @@ module Arel
   class Compound < Relation
     attr_reader :relation
     hash_on :relation
-    delegate :joins, :selects, :orders, :groupings, :inserts, :taken,
+    delegate :joins, :selects, :join?, :orders, :groupings, :inserts, :taken,
              :skipped, :name, :aggregation?, :column_for,
              :engine, :table, :table_sql,
              :to => :relation
@@ -10,5 +10,9 @@ module Arel
     def attributes
       @attributes ||= relation.attributes.collect { |a| a.bind(self) }
     end
+    
+    def relation_for(attribute)
+      join? && relation.relation_for(attribute) || self[attribute] && self
+    end
   end
 end
 \ No newline at end of file
diff --git a/lib/arel/relations/join.rb b/lib/arel/relations/join.rb
index d42af5a499..05ed6efc23 100644
--- a/lib/arel/relations/join.rb
+++ b/lib/arel/relations/join.rb
@@ -49,16 +49,18 @@ module Arel
       end
     end
     
+    def aggregation?
+      relation1.aggregation? or relation2.aggregation?
+    end
+    
+    def join?
+      true
+    end
+    
     private
     # FIXME - make instance method
     def externalize(relation)
       relation.aggregation?? Aggregation.new(relation) : relation
     end
   end
-  
-  class Relation
-    def relation_for(attribute)
-      self[attribute] && self
-    end
-  end
 end
 \ No newline at end of file
diff --git a/lib/arel/relations/nil.rb b/lib/arel/relations/nil.rb
index b0d97dd174..34f9ea8722 100644
--- a/lib/arel/relations/nil.rb
+++ b/lib/arel/relations/nil.rb
@@ -1,6 +1,7 @@
 module Arel
   class Nil < Relation
-    def table; self end
+    include Recursion::BaseCase
+    
     def table_sql(formatter = nil); '' end
     def relation_for(attribute); nil end
     def name; '' end
diff --git a/lib/arel/relations/recursion.rb b/lib/arel/relations/recursion.rb
index 848b059507..c5ca171fd2 100644
--- a/lib/arel/relations/recursion.rb
+++ b/lib/arel/relations/recursion.rb
@@ -8,6 +8,18 @@ module Arel
       def table_sql(formatter = Sql::TableReference.new(self))
         formatter.table self
       end
+      
+      def relation_for(attribute)
+        self[attribute] && self
+      end
+      
+      def join?
+        false
+      end
+      
+      def aggregation?
+        false
+      end
     end
   end
 end
 \ No newline at end of file
diff --git a/lib/arel/relations/relation.rb b/lib/arel/relations/relation.rb
index c576033938..884b743f20 100644
--- a/lib/arel/relations/relation.rb
+++ b/lib/arel/relations/relation.rb
@@ -39,10 +39,6 @@ module Arel
       @christener ||= Sql::Christener.new
     end
     
-    def aggregation?
-      false
-    end
-    
     module Enumerable
       include ::Enumerable