2 files changed, 11 insertions, 6 deletions
diff --git a/lib/arel/expressions.rb b/lib/arel/expressions.rb
index fa18f15b67..d40268c292 100644
--- a/lib/arel/expressions.rb
+++ b/lib/arel/expressions.rb
@@ -5,23 +5,24 @@ module Arel
     end
 
     def sum
-      Nodes::Sum.new [self], Nodes::SqlLiteral.new('sum_id')
+      Nodes::Sum.new [self]
     end
 
     def maximum
-      Nodes::Max.new [self], Nodes::SqlLiteral.new('max_id')
+      Nodes::Max.new [self]
     end
 
     def minimum
-      Nodes::Min.new [self], Nodes::SqlLiteral.new('min_id')
+      Nodes::Min.new [self]
     end
 
     def average
-      Nodes::Avg.new [self], Nodes::SqlLiteral.new('avg_id')
+      Nodes::Avg.new [self]
     end
 
     def extract field
       Nodes::Extract.new [self], field
     end
+
   end
 end
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 8c63070084..ae1b7930af 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -436,8 +436,12 @@ module Arel
       end
 
       def visit_Arel_Nodes_Grouping o, collector
-        collector << "("
-        visit(o.expr, collector) << ")"
+        if o.expr.is_a? Nodes::Grouping
+          visit(o.expr, collector)
+        else
+          collector << "("
+          visit(o.expr, collector) << ")"
+        end
       end
 
       def visit_Arel_SelectManager o, collector