I have a similar kind of issue with my Execution Plan showing as Clustered Index Update cost as 98%

Whereas in my Update query I am not even updating the Clustered Index/Primary key column.

I am just using the primary key column in the where clause for equating with the parameter value.

My update script is:

BEGIN TRAN

update [MM_TItemCurrentStock] set

[OpeningStock] = 0,

[InwardStock] = 0,

[OutwardStock] = 0,

[ClosingStock] = 0,

[OpeningRate] = 0,

[OpeningValue] = 0,

[InwardRate] = 0,

[InwardValue] = 0,

[OutwardRate] = 0,

[OutwardValue] = 0,

[ClosingRate] = 0,

[ClosingValue]= 0,

[DirectSaleStock]= 0,

[DirectSaleRate]= 0,

[DirectSaleValue]= 0,

[TransferStock]= 0,

[TransferRate]= 0,

[TransferValue]= 0

where (OrganizationUnitID = @LoginOrganizationUnitID)

COMMIT

Table MM_TItemCurrentStock has primary key constraint on columns: ItemID and OrganizationUnitID

Can anybody please help me to resolve this higher Clustered Index Update Cost issue. Thanks in advance!!