SQL Server 2025

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create table franck ( val int unique );
insert into franck values (-1),(1) ;

2 rows affected


select val from franck;


val


-1

1


update franck set val=-val;

2 rows affected


select val from franck;


val


-1

1


SELECT name, snapshot_isolation_state_desc 
FROM sys.databases 
WHERE name = DB_NAME();


name
snapshot_isolation_state_desc


fiddle_c589a143051f4a9380867cf3bba3f120
ON


SET SHOWPLAN_ALL ON
update franck set val=-val;


StmtText
StmtId
NodeId
Parent
PhysicalOp
LogicalOp
Argument
DefinedValues
EstimateRows
EstimateIO
EstimateCPU
AvgRowSize
TotalSubtreeCost
OutputList
Warnings
Type
Parallel
EstimateExecutions


update franck set val=-val;
1
1
0
null
null
1
null
2.7
null
null
null
0.03703665
null
null
UPDATE
False
null

  |--Index Update(OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[UQ__franck__DDB0736E90E00462]), SET:(Insert, [Bmk10041014] = [Bmk1004],[val1015] = [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]), SET:(Update, [Bmk10041014] = [Bmk1004]) ACTION:([Act1013]))
1
3
1
Index Update
Update
OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[UQ__franck__DDB0736E90E00462]), SET:(Insert, [Bmk10041014] = [Bmk1004],[val1015] = [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]), SET:(Update, [Bmk10041014] = [Bmk1004]) ACTION:([Act1013])
null
2.7
0.01236487
2.7E-06
9
0.03703665
null
null
PLAN_ROW
False
1

       |--Collapse(GROUP BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]))
1
4
3
Collapse
Collapse
GROUP BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val])
null
2.7
0
6.3E-06
23
0.02466908
[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Act1013]
null
PLAN_ROW
False
1

            |--Sort(ORDER BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] ASC, [Act1013] ASC))
1
5
4
Sort
Sort
ORDER BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] ASC, [Act1013] ASC)
null
3.6
0.01126126
0.0001104013
23
0.02466278
[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Act1013]
null
PLAN_ROW
False
1

                 |--Filter(WHERE:(NOT [Expr1012]))
1
6
5
Filter
Filter
WHERE:(NOT [Expr1012])
null
3.6
0
1.52E-06
23
0.01329112
[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Act1013]
null
PLAN_ROW
False
1

                      |--Split
1
7
6
Split
Split
null
[Act1013]
4
0
3E-06
24
0.0132896
[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1012], [Act1013]
null
PLAN_ROW
False
1

                           |--Table Update(OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck]), SET:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = [Expr1003]))
1
8
7
Table Update
Update
OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck]), SET:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = [Expr1003])
null
2
0.01
2E-06
24
0.0132866
[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [val_OLD], [Expr1012]
null
PLAN_ROW
False
1

                                |--Compute Scalar(DEFINE:([Expr1012]=[Expr1012]))
1
9
8
Compute Scalar
Compute Scalar
DEFINE:([Expr1012]=[Expr1012])
[Expr1012]=[Expr1012]
2
0
2E-07
20
0.0032846
[Bmk1000], [Expr1003], [Expr1012]
null
PLAN_ROW
False
1

                                     |--Compute Scalar(DEFINE:([Expr1012]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END))
1
10
9
Compute Scalar
Compute Scalar
DEFINE:([Expr1012]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END)
[Expr1012]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END
2
0
2E-07
20
0.0032846
[Bmk1000], [Expr1003], [Expr1012]
null
PLAN_ROW
False
1

                                          |--Compute Scalar(DEFINE:([Expr1003]= -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1007]=CASE WHEN [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = ( -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]) THEN (1) ELSE (0) END))
1
11
10
Compute Scalar
Compute Scalar
DEFINE:([Expr1003]= -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1007]=CASE WHEN [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = ( -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]) THEN (1) ELSE (0) END)
[Expr1003]= -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1007]=CASE WHEN [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = ( -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]) THEN (1) ELSE (0) END
2
0
2E-07
20
0.0032844
[Bmk1000], [Expr1003], [Expr1007]
null
PLAN_ROW
False
1

                                               |--Table Scan(OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck]))
1
12
11
Table Scan
Table Scan
OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck])
[Bmk1000], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]
2
0.0032035
8.07E-05
19
0.0032842
[Bmk1000], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]
null
PLAN_ROW
False
1

StmtText	StmtId	NodeId	Parent	PhysicalOp	LogicalOp	Argument	DefinedValues	EstimateRows	EstimateIO	EstimateCPU	AvgRowSize	TotalSubtreeCost	OutputList	Warnings	Type	Parallel	EstimateExecutions
update franck set val=-val;	1	1	0	null	null	1	null	2.7	null	null	null	0.03703665	null	null	UPDATE	False	null
\|--Index Update(OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[UQ__franck__DDB0736E90E00462]), SET:(Insert, [Bmk10041014] = [Bmk1004],[val1015] = [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]), SET:(Update, [Bmk10041014] = [Bmk1004]) ACTION:([Act1013]))	1	3	1	Index Update	Update	OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[UQ__franck__DDB0736E90E00462]), SET:(Insert, [Bmk10041014] = [Bmk1004],[val1015] = [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]), SET:(Update, [Bmk10041014] = [Bmk1004]) ACTION:([Act1013])	null	2.7	0.01236487	2.7E-06	9	0.03703665	null	null	PLAN_ROW	False	1
\|--Collapse(GROUP BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]))	1	4	3	Collapse	Collapse	GROUP BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val])	null	2.7	0	6.3E-06	23	0.02466908	[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Act1013]	null	PLAN_ROW	False	1
\|--Sort(ORDER BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] ASC, [Act1013] ASC))	1	5	4	Sort	Sort	ORDER BY:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] ASC, [Act1013] ASC)	null	3.6	0.01126126	0.0001104013	23	0.02466278	[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Act1013]	null	PLAN_ROW	False	1
\|--Filter(WHERE:(NOT [Expr1012]))	1	6	5	Filter	Filter	WHERE:(NOT [Expr1012])	null	3.6	0	1.52E-06	23	0.01329112	[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Act1013]	null	PLAN_ROW	False	1
\|--Split	1	7	6	Split	Split	null	[Act1013]	4	0	3E-06	24	0.0132896	[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1012], [Act1013]	null	PLAN_ROW	False	1
\|--Table Update(OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck]), SET:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = [Expr1003]))	1	8	7	Table Update	Update	OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck]), SET:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = [Expr1003])	null	2	0.01	2E-06	24	0.0132866	[Bmk1004], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [val_OLD], [Expr1012]	null	PLAN_ROW	False	1
\|--Compute Scalar(DEFINE:([Expr1012]=[Expr1012]))	1	9	8	Compute Scalar	Compute Scalar	DEFINE:([Expr1012]=[Expr1012])	[Expr1012]=[Expr1012]	2	0	2E-07	20	0.0032846	[Bmk1000], [Expr1003], [Expr1012]	null	PLAN_ROW	False	1
\|--Compute Scalar(DEFINE:([Expr1012]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END))	1	10	9	Compute Scalar	Compute Scalar	DEFINE:([Expr1012]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END)	[Expr1012]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END	2	0	2E-07	20	0.0032846	[Bmk1000], [Expr1003], [Expr1012]	null	PLAN_ROW	False	1
\|--Compute Scalar(DEFINE:([Expr1003]= -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1007]=CASE WHEN [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = ( -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]) THEN (1) ELSE (0) END))	1	11	10	Compute Scalar	Compute Scalar	DEFINE:([Expr1003]= -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1007]=CASE WHEN [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = ( -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]) THEN (1) ELSE (0) END)	[Expr1003]= -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val], [Expr1007]=CASE WHEN [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val] = ( -[fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]) THEN (1) ELSE (0) END	2	0	2E-07	20	0.0032844	[Bmk1000], [Expr1003], [Expr1007]	null	PLAN_ROW	False	1
\|--Table Scan(OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck]))	1	12	11	Table Scan	Table Scan	OBJECT:([fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck])	[Bmk1000], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]	2	0.0032035	8.07E-05	19	0.0032842	[Bmk1000], [fiddle_c589a143051f4a9380867cf3bba3f120].[dbo].[franck].[val]	null	PLAN_ROW	False	1