Heap big table with performance issues

Question

I have a business case where I need to store all details about invoices from vehicle workshop (invoice number, dealer,vehicle number, peace, nature of service , ...). I have more than 50 columns which are all selected in the same query.

In my treatment I need to do some specific treatment in order to get cleansed data and some basic transformations. The problem that I'm facing it is that I have no business key to be able to create a primary key because each line of my workshop data represents an invoice details (like a piece reparation) and sometimes I have the same duplicated lines because there are the same operation more than once in the workshop.

So I find myself with a Heap table without any clustered index. So I tried to create some non clustered index to improve performance but it is not really working and every time I load more data the select query takes more times than before.

I checked the execution plan and I observed that the main reason of my problem is RID lookup (Heap) which costs more than 85%

I need some help here ^^ and I already had the idea to create a composite index which define an invoice but it will not be unique in my data set? What do you think?

Answer 1

聚集索引不需要是唯一的（如果不是，SQL 会添加一个内部的“唯一标识符”，以便行可以相互区分），所以继续创建一个！