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)\'
      Function materialize (children 1)
       ExpressionList (children 1)
        Literal UInt64_2
      Literal Int64_-2