SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function dateDiff (children 1)
     ExpressionList (children 3)
      Literal \'second\'
      Function materialize (children 1)
       ExpressionList (children 1)
        Function toDateTime (children 1)
         ExpressionList (children 2)
          Literal \'2015-08-18 00:00:00\'
          Literal \'UTC\'
      Function toDateTime64 (children 1)
       ExpressionList (children 3)
        Literal \'2015-08-18 00:00:10\'
        Literal UInt64_3
        Literal \'UTC\'