tsql - ORDER BY キーワードを持たない更新クエリのインデックス プランで Sort 演算子を避ける

Question

更新クエリがあります:-

Update PM.Contractual_Allowances  Set Provider_ID = 3  Where Tenant_ID = 1 and Carrier_ID = 203

この上記のクエリでは、以下のように実行計画を取得しています。

ORDER BY 句がないときにソート演算子を取得する理由と、それを回避するためにできることを理解しようとしています。

以下はテキストの計画です (別名 'Showplan_text'):

|--Sequence
   |--Index Update(OBJECT:([Ntier_Master].[PM].[Contractual_Allowances].[IX_Contractual_Allowances_Provider_ID_Tenant_ID]), SET:([Contractual_Allowance_ID1043] = [Ntier_Master].[PM].[Contractual_Allowances].[Contractual_Allowance_ID],[Provider_ID1044] = [Ntier_Master].[PM].[Contractual_Allowances].[Provider_ID],[Tenant_ID1045] = [Ntier_Master].[PM].[Contractual_Allowances].[Tenant_ID]) WITH ORDERED PREFETCH ACTION:([Act1042]))
   |    |--Sort(ORDER BY:([Ntier_Master].[PM].[Contractual_Allowances].[Provider_ID] ASC, [Ntier_Master].[PM].[Contractual_Allowances].[Tenant_ID] ASC, [Ntier_Master].[PM].[Contractual_Allowances].[Contractual_Allowance_ID] ASC, [Act1042] ASC))
   |         |--Filter(WHERE:(NOT [Expr1038]))
   |              |--Table Spool
   |                   |--Split
   |                        |--Clustered Index Update(OBJECT:([Ntier_Master].[PM].[Contractual_Allowances].[PK_Contractual_Allowances_Contractual_Allowance_ID]), SET:([Ntier_Master].[PM].[Contractual_Allowances].[Provider_ID] = [Expr1033],[Ntier_Master].[PM].[Contractual_Allowances].[Contractual_Allowance_TS] = [Expr1003]))
   |                             |--Compute Scalar(DEFINE:([Expr1038]=[Expr1038], [Expr1039]=[Expr1039]))
   |                                  |--Compute Scalar(DEFINE:([Expr1038]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END, [Expr1039]=CASE WHEN [Expr1007] THEN (1) ELSE (0) END))
   |                                       |--Compute Scalar(DEFINE:([Expr1033]=(3)))
   |                                            |--Compute Scalar(DEFINE:([Expr1007]=CASE WHEN [Ntier_Master].[PM].[Contractual_Allowances].[Provider_ID] = (3) THEN (1) ELSE (0) END))
   |                                                 |--Compute Scalar(DEFINE:([Expr1003]=gettimestamp((10))))
   |                                                      |--Clustered Index Scan(OBJECT:([Ntier_Master].[PM].[Contractual_Allowances].[PK_Contractual_Allowances_Contractual_Allowance_ID]),  WHERE:([Ntier_Master].[PM].[Contractual_Allowances].[Tenant_ID]=(1) AND [Ntier_Master].[PM].[Contractual_Allowances].[Carrier_ID]=(203)) ORDERED FORWARD)
   |--Index Update(OBJECT:([Ntier_Master].[PM].[Contractual_Allowances].[IX_Contractual_Allowances_Carrier_ID_Location_ID_Department_ID_Tenant_ID]), SET:([Contractual_Allowance_ID1046] = [Ntier_Master].[PM].[Contractual_Allowances].[Contractual_Allowance_ID],[Modifiers1047] = [Ntier_Master].[PM].[Contractual_Allowances].[Modifiers],[Carrier_ID1048] = [Ntier_Master].[PM].[Contractual_Allowances].[Carrier_ID],[Procedure_Code_ID1049] = [Ntier_Master].[PM].[Contractual_Allowances].[Procedure_Code_ID],[Location_ID1050] = [Ntier_Master].[PM].[Contractual_Allowances].[Location_ID],[Provider_ID1051] = [Ntier_Master].[PM].[Contractual_Allowances].[Provider_ID],[Department_ID1052] = [Ntier_Master].[PM].[Contractual_Allowances].[Department_ID],[Tenant_ID1053] = [Ntier_Master].[PM].[Contractual_Allowances].[Tenant_ID]) WITH ORDERED PREFETCH ACTION:([Act1042]))
        |--Sort(ORDER BY:([Ntier_Master].[PM].[Contractual_Allowances].[Carrier_ID] ASC, [Ntier_Master].[PM].[Contractual_Allowances].[Location_ID] ASC, [Ntier_Master].[PM].[Contractual_Allowances].[Department_ID] ASC, [Ntier_Master].[PM].[Contractual_Allowances].[Tenant_ID] ASC, [Ntier_Master].[PM].[Contractual_Allowances].[Contractual_Allowance_ID] ASC, [Act1042] ASC))
             |--Filter(WHERE:(NOT [Expr1039]))
                  |--Table Spool




 CREATE NONCLUSTERED INDEX IX_Contractual_Allowances_Location_ID_Tenant_ID ON PM.Contractual_Allowances (  Location_ID ASC  , Tenant_ID ASC  )   WITH (  PAD_INDEX =  OFF ,FILLFACTOR = 100  ,SORT_IN_TEMPDB = OFF , IGNORE_DUP_KEY = OFF , STATISTICS_NORECOMPUTE = OFF , DROP_EXISTING = ON , ONLINE = OFF , ALLOW_ROW_LOCKS = ON , ALLOW_PAGE_LOCKS = ON  ) ON [PRIMARY ] 
 CREATE NONCLUSTERED INDEX IX_Contractual_Allowances_Provider_ID_Tenant_ID ON PM.Contractual_Allowances (  Provider_ID ASC  , Tenant_ID ASC  )   WITH (  PAD_INDEX =  OFF ,FILLFACTOR = 100  ,SORT_IN_TEMPDB = OFF , IGNORE_DUP_KEY = OFF , STATISTICS_NORECOMPUTE = OFF , DROP_EXISTING = ON , ONLINE = OFF , ALLOW_ROW_LOCKS = ON , ALLOW_PAGE_LOCKS = ON  ) ON [PRIMARY ] 
 CREATE NONCLUSTERED INDEX IX_Contractual_Allowances_Carrier_ID_Current_Effective_Date_Tenant_ID ON PM.Contractual_Allowances (  Carrier_ID ASC  , Current_Effective_Date ASC  , Tenant_ID ASC  )   WITH (  PAD_INDEX =  OFF ,FILLFACTOR = 100  ,SORT_IN_TEMPDB = OFF , IGNORE_DUP_KEY = OFF , STATISTICS_NORECOMPUTE = OFF , DROP_EXISTING = ON , ONLINE = OFF , ALLOW_ROW_LOCKS = ON , ALLOW_PAGE_LOCKS = ON  ) ON [PRIMARY ] 
 CREATE NONCLUSTERED INDEX IX_Contractual_Allowances_Carrier_ID_Location_ID_Department_ID_Tenant_ID ON PM.Contractual_Allowances (  Carrier_ID ASC  , Location_ID ASC  , Department_ID ASC  , Tenant_ID ASC  )   INCLUDE ( Modifiers , Procedure_Code_ID , Provider_ID )  WITH (  PAD_INDEX =  OFF ,FILLFACTOR = 100  ,SORT_IN_TEMPDB = OFF , IGNORE_DUP_KEY = OFF , STATISTICS_NORECOMPUTE = OFF , DROP_EXISTING = ON , ONLINE = OFF , ALLOW_ROW_LOCKS = ON , ALLOW_PAGE_LOCKS = ON  ) ON [PRIMARY ] 
CREATE NONCLUSTERED INDEX IX_Contractual_Allowances_Procedure_Code_ID_Tenant_ID ON PM.Contractual_Allowances (  Procedure_Code_ID ASC  , Tenant_ID ASC  )   WITH (  PAD_INDEX =  OFF ,FILLFACTOR = 100  ,SORT_IN_TEMPDB = OFF , IGNORE_DUP_KEY = OFF , STATISTICS_NORECOMPUTE = OFF , DROP_EXISTING = ON , ONLINE = OFF , ALLOW_ROW_LOCKS = ON , ALLOW_PAGE_LOCKS = ON  ) ON [PRIMARY ]