SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function substring (children 1)
     ExpressionList (children 3)
      Function CAST (children 1)
       ExpressionList (children 2)
        Literal \'abcdefgh\'
        Literal \'FixedString(8)\'
      Literal UInt64_2
      Function materialize (children 1)
       ExpressionList (children 1)
        Literal Int64_-2