def prefetch_primary_key?(table_name = nil)
      return true if table_name.nil?
      table_name = table_name.to_s
      primary_keys(table_name.to_s).size == 0
    end
def prefetch_primary_key?(table_name = nil)
      return true if table_name.nil?
      table_name = table_name.to_s
      primary_keys(table_name.to_s).size == 0
    end
If true, next_sequence_value is called before each insert statement
 to set the record's primary key.
 By default DB2 for i supports IDENTITY_VAL_LOCAL for tables that have
 one primary key.