SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function in (children 1)
     ExpressionList (children 2)
      Literal UInt64_1000000
      Subquery (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 1)
           Function materialize (children 1)
            ExpressionList (children 1)
             Function getSetting (children 1)
              ExpressionList (children 1)
               Literal \'max_threads\'
