make table aliases cheaper to allocate

2 files changed, 4 insertions, 8 deletions

diff --git a/lib/arel/nodes/table_alias.rb b/lib/arel/nodes/table_alias.rb
index 7ec1fad272..60da7b19f3 100644
--- a/lib/arel/nodes/table_alias.rb
+++ b/lib/arel/nodes/table_alias.rb
@@ -1,20 +1,16 @@
 module Arel
   module Nodes
     class TableAlias
-      attr_reader :name, :relation, :columns
+      attr_reader :name, :relation
       alias :table_alias :name
 
       def initialize name, relation
         @name     = name
         @relation = relation
-        @columns  = relation.columns.map { |column|
-          column.dup.tap { |col| col.relation = self }
-        }
       end
 
       def [] name
-        name = name.to_sym
-        columns.find { |column| column.name == name }
+        Attribute.new self, name
       end
     end
   end
diff --git a/lib/arel/table.rb b/lib/arel/table.rb
index fe12427d1b..6f29a02e56 100644
--- a/lib/arel/table.rb
+++ b/lib/arel/table.rb
@@ -34,8 +34,8 @@ module Arel
       end
     end
 
-    def alias
-      Nodes::TableAlias.new("#{name}_2", self).tap do |node|
+    def alias name = "#{self.name}_2"
+      Nodes::TableAlias.new(name, self).tap do |node|
         @aliases << node
       end
     end