Abstract: An apparatus and method perform block-level sampling on a database, process the data to generate one or more matrices, and process the one or more matrices to generate a clustering factor for a selected index. In addition, the apparatus and method of the preferred embodiments allow the distribution of the clustering factor to be determined across a range, thereby allowing the identification of ranges where the clustering factor is high and ranges where the clustering factor is low. The clustering factor distribution can then be used to predict the memory paging performance of a search that uses an existing or a potential index that corresponds to the sampled data, and can therefore be used to predict the performance of searching the database using an existing or potential index for a particular database query.