The problem here is that the inserts are not in an ever increasing order, possible option would be adding an Identity column for the primary key and then a unique index instead of the old pk, something like this

😎

CREATE TABLE dbo.Inventory

(

EAN bigint NOT NULL

,Day smalldatetime NOT NULL

,State int NOT NULL

,Quantity int NULL

,StockValue float NULL

,CONSTRAINT PK_Inventory PRIMARY KEY CLUSTERED

(

EAN ASC,

Day ASC,

State ASC

)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

) ON [PRIMARY];

/* Replacing the existing PK with an Identity column and adding a unique index */

ALTER TABLE dbo.Inventory ADD Inventory_ID BIGINT IDENTITY(1,1) NOT NULL;

ALTER TABLE dbo.Inventory DROP CONSTRAINT PK_Inventory;

ALTER TABLE dbo.Inventory ADD CONSTRAINT PK_DBO_INVENTORY_INVENTORY_ID PRIMARY KEY CLUSTERED (Inventory_ID ASC);

CREATE UNIQUE NONCLUSTERED INDEX UNQNCLIDX_DBO_INVENTORY_EAN_DAY_STATE ON dbo.Inventory ( EAN ASC , Day ASC , State ASC );

70K p. day mounts only to 25-26 million a year, shouldn't be to hard to handle;-)