SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 5)
   ExpressionList (children 1)
    Identifier x
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier partial_sort_opt_bug
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier x
   Literal UInt64_2000
   Set
