Plano de execução para COMPUTE BY

Eu entendo que o COMPUTE BYrecurso está obsoleto. Por curiosidade, gostaria de saber como o processador de consulta executa uma COMPUTE BYconsulta. O plano de execução não contém nenhuma dica:

Como o processador de consultas é executado COMPUTE BYe como posso obter um plano de execução preciso?

Aqui está um pouco de T-SQL para brincar:

 create table employee(
    ID          int,
    name        nvarchar (10),
    salary      int,
    start_date  datetime,
    city        nvarchar (10),
    region      char (1))
GO
insert into employee (ID, name,    salary, start_date, city,       region)
              values (1,  'Jason', 40420,  '02/01/94', 'New York', 'W')

insert into employee (ID, name,    salary, start_date, city,       region)
              values (2,  'Robert',14420,  '01/02/95', 'Vancouver','N')
GO

insert into employee (ID, name,    salary, start_date, city,       region)
              values (3,  'Celia', 24020,  '12/03/96', 'Toronto',  'W')

insert into employee (ID, name,    salary, start_date, city,       region)
              values (4,  'Linda', 40620,  '11/04/97', 'New York', 'N')
GO

insert into employee (ID, name,    salary, start_date, city,       region)
              values (5,  'David', 80026,  '10/05/98', 'Vancouver','W')
GO

insert into employee (ID, name,    salary, start_date, city,       region)
              values (6,  'James', 70060,  '09/06/99', 'Toronto',  'N')
GO

insert into employee (ID, name,    salary, start_date, city,       region)
              values (7,  'Alison',90620,  '08/07/00', 'New York', 'W')
GO

insert into employee (ID, name,    salary, start_date, city,       region)
              values (8,  'Chris', 26020,  '07/08/01', 'Vancouver','N')
GO

insert into employee (ID, name,    salary, start_date, city,       region)
              values (9,  'Mary',  60020,  '06/09/02', 'Toronto',  'W')
GO

select * from employee
GO
/*
ID          name       salary      start_date              city       region
----------- ---------- ----------- ----------------------- ---------- ------
          1 Jason            40420 1994-02-01 00:00:00.000 New York   W
          2 Robert           14420 1995-01-02 00:00:00.000 Vancouver  N
          3 Celia            24020 1996-12-03 00:00:00.000 Toronto    W
          4 Linda            40620 1997-11-04 00:00:00.000 New York   N
          5 David            80026 1998-10-05 00:00:00.000 Vancouver  W
          6 James            70060 1999-09-06 00:00:00.000 Toronto    N
          7 Alison           90620 2000-08-07 00:00:00.000 New York   W
          8 Chris            26020 2001-07-08 00:00:00.000 Vancouver  N
          9 Mary             60020 2002-06-09 00:00:00.000 Toronto    W
*/


-- COMPUTE BY
SELECT salary, Name
FROM Employee
ORDER BY ID, Name
COMPUTE SUM(Salary)
GO

/*
salary      Name
----------- ----------
      40420 Jason
      14420 Robert
      24020 Celia
      40620 Linda
      80026 David
      70060 James
      90620 Alison
      26020 Chris
      60020 Mary
sum
===========
     446226
*/

GO

drop table employee

( Fonte )

Os resultados deste single SELECTsão: