Consistently use LOWER() for uniqueness validations (rather than mixing with...

Consistently use LOWER() for uniqueness validations (rather than mixing with UPPER()) so the database can always use a functional index on the lowercased column. Closes #6495.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5434 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Consistently use LOWER() for uniqueness validations (rather than mixing with UPPER()) so the database can always use a functional index on the lowercased column.  #6495 [Si]
+
 * SQLite: fix calculations workaround, remove count(distinct) query rewrite, cleanup test connection scripts.  [Jeremy Kemper]
 
 * SQLite: count(distinct) queries supported in >= 3.2.6.  #6544 [Bob Silva]

activerecord/lib/active_record/validations.rb

@@ -533,8 +533,8 @@ def validates_uniqueness_of(*attr_names)
             condition_sql = "#{record.class.table_name}.#{attr_name} #{attribute_condition(value)}"
             condition_params = [value]
           else
-            condition_sql = "UPPER(#{record.class.table_name}.#{attr_name}) #{attribute_condition(value)}"
-            condition_params = [value.upcase]
+            condition_sql = "LOWER(#{record.class.table_name}.#{attr_name}) #{attribute_condition(value)}"
+            condition_params = [value.downcase]
           end
           if scope = configuration[:scope]
             Array(scope).map do |scope_item|