validate_index_length!

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 1274
      def validate_index_length!(table_name, new_name) # :nodoc:
        if new_name.length > allowed_index_name_length
          raise ArgumentError, "Index name '#{new_name}' on table '#{table_name}' is too long; the limit is #{allowed_index_name_length} characters"
        end
      end