Freeze columns only once per Result

Conflicts:
	activerecord/lib/active_record/result.rb

1 files changed, 9 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/result.rb b/activerecord/lib/active_record/result.rb
index 9ceab2eabc..b8d2cd2866 100644
--- a/activerecord/lib/active_record/result.rb
+++ b/activerecord/lib/active_record/result.rb
@@ -26,9 +26,15 @@ module ActiveRecord
 
     private
     def hash_rows
-      @hash_rows ||= @rows.map { |row|
-        Hash[@columns.zip(row)]
-      }
+      @hash_rows ||=
+        begin
+          # We freeze the strings to prevent them getting duped when
+          # used as keys in ActiveRecord::Model's @attributes hash
+          columns = @columns.map { |c| c.dup.freeze }
+          @rows.map { |row|
+            Hash[columns.zip(row)]
+          }
+        end
     end
   end
 end