Clustered   Each table can have at most one clustered index. In some cases, a clustered index can provide significantly more benefit than an unclustered index. See Using clustered indexes.

Pages   The estimated number of database pages required to hold the index if you choose to create it. See Table and page sizes.

Relative Benefit   A number from one to ten, indicating the estimated overall benefit of creating the specified index. A higher number indicates a greater benefit.

The relative benefit is computed using an internal algorithm, separately from the Total Cost Benefit column. There are several factors included in estimating the relative benefit that do not appear in the total cost benefit. For example, it can happen that the presence of one index dramatically affects the benefits associated with a second index. In this case, the relative benefit attempts to estimate the separate impact of each index.

For more information, see Implementing Index Consultant results.

Total Benefit   The cost decrease associated with the index, summed over all operations in the tracing session, measured in internal units of cost (the cost model). See How the optimizer works.

Update Cost   Adding an index introduces cost, both in additional storage space and in extra work required when data is modified. The Update Cost column is an estimate of the additional maintenance cost associated with an index. It is measured in internal units of cost.

Total Cost Benefit   The total benefit minus the update cost associated with the index.