statistics io reports the number of times a query accessed a particular table. A “scan” can represent any of these access methods:
A table scan.
An access via a clustered index. Each time the query starts at the root page of the index and follows pointers to the data pages, it is counted as a scan.
An access via a nonclustered index. Each time the query starts at the root page of the index and follows pointers to the leaf level of the index (for a covered query) or to the data pages, it is counted.
If queries run in parallel, each worker process access to the table is counted as a scan.
Use showplan, as described in Chapter 36, “Using set showplan,” to determine which access method is used.
