use master;
set ansi_nulls, quoted_identifier, xact_abort on;
go

create database TestData;
alter database TestData set recovery simple;
go

use TestData;
go

create table dbo.t_clustered (id int identity not null primary key, v int null, filler char(100) null);
create table dbo.t_heap (id int identity not null, v int null, filler char(100) null);

insert into dbo.t_clustered
 (v)
output
 inserted.v into dbo.t_heap (v)
 select top (1000000)
  1
 from
  master.dbo.spt_values a cross join
  master.dbo.spt_values b;

select
 sum(page_count) as t_clustered__total_pages,
 sum(case when index_level > 0 then page_count else 0 end) as t_clustered__nonleaf_pages
from
 sys.dm_db_index_physical_stats(db_id(), object_id('dbo.t_clustered'), null, null, 'detailed');

select
 sum(page_count) as t_heap__total_pages
from
 sys.dm_db_index_physical_stats(db_id(), object_id('dbo.t_heap'), null, null, 'detailed');
go

-- запретим prefetch и read ahead
dbcc traceon(652, -1);
dbcc traceon(8744, -1);
go

use master;
go

-- очистим BP от данных из TestData
alter database TestData set offline with rollback immediate;
alter database TestData set online;
go

print '--- Seril plan ------------------------------------';
declare @c bigint;
set statistics xml, io on;
select @c = count(v) from TestData.dbo.t_clustered option(maxdop 1);
select @c = count(v) from TestData.dbo.t_heap option(maxdop 1);
set statistics xml, io off;
go

-- очистим BP от данных из TestData
alter database TestData set offline with rollback immediate;
alter database TestData set online;
go

print '--- Parallel plan ------------------------------------';
declare @c bigint;
set statistics xml, io on;
select @c = count(v) from TestData.dbo.t_clustered option (use hint('enable_parallel_plan_preference'));
select @c = count(v) from TestData.dbo.t_heap option (use hint('enable_parallel_plan_preference'));
set statistics xml, io off;
go

use master;
alter database TestData set single_user with rollback immediate;
drop database TestData;
go

dbcc traceoff(652, -1);
dbcc traceoff(8744, -1);
go

--- Seril plan ------------------------------------
Table 't_clustered'. Scan count 1, logical reads 14495, physical reads 14495, page server reads 0, read-ahead reads 0, page server read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob page server reads 0, lob read-ahead reads 0, lob page server read-ahead reads 0.

Table 't_heap'. Scan count 1, logical reads 14493, physical reads 14493, page server reads 0, read-ahead reads 0, page server read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob page server reads 0, lob read-ahead reads 0, lob page server read-ahead reads 0.

--- Parallel plan ------------------------------------
Table 't_clustered'. Scan count 5, logical reads 14652, physical reads 14547, page server reads 0, read-ahead reads 0, page server read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob page server reads 0, lob read-ahead reads 0, lob page server read-ahead reads 0.

Table 't_heap'. Scan count 5, logical reads 14493, physical reads 14493, page server reads 0, read-ahead reads 0, page server read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob page server reads 0, lob read-ahead reads 0, lob page server read-ahead reads 0.