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
      Function materialize (children 1)
       ExpressionList (children 1)
        Literal Int64_-2