• Since there is no complete table definition will be not accurate suggestion from us.plus no idea either you have clustered index on tables or not ?

    anyways

    Order table will have index on InvoiceID and InvoiceNumber

    OrderLines will have ix_test on orderLines(InvoiceId, ProductID,status) Include(.....)

    and cardinality high for left most column will work better,like sequence InvoiceId, ProductID,status

    -------Bhuvnesh----------
    I work only to learn Sql Server...though my company pays me for getting their stuff done;-)