2 files changed, 25 insertions, 0 deletions
diff --git a/lib/arel/algebra/relations/row.rb b/lib/arel/algebra/relations/row.rb
index 2d63498452..3731dd9696 100644
--- a/lib/arel/algebra/relations/row.rb
+++ b/lib/arel/algebra/relations/row.rb
@@ -17,5 +17,9 @@ module Arel
     def bind(relation)
       Row.new(relation, tuple)
     end
+    
+    def combine(other, relation)
+      Row.new(relation, tuple + other.tuple)
+    end
   end
 end
 \ No newline at end of file
diff --git a/lib/arel/engines/memory/relations/operations.rb b/lib/arel/engines/memory/relations/operations.rb
index 8e03aca7b1..e35fbe3234 100644
--- a/lib/arel/engines/memory/relations/operations.rb
+++ b/lib/arel/engines/memory/relations/operations.rb
@@ -37,4 +37,25 @@ module Arel
       raise NotImplementedError
     end
   end
+  
+  class Alias < Compound
+    def eval
+      unoperated_rows
+    end
+  end
+  
+  class Join < Relation
+    def eval
+      result = []
+      relation1.eval.each do |row1|
+        relation2.eval.each do |row2|
+          combined_row = row1.combine(row2, self)
+          if predicates.all? { |p| p.eval(combined_row) }
+            result << combined_row
+          end
+        end
+      end
+      result
+    end
+  end
 end
 \ No newline at end of file