
154 Automated Physical Database Design and Tuning
instances. We next discuss an approach to limit the set of views to consider
in bottom-up enumeration strategies.
8.4.1 Restricting the Enumeration Space
An observation that motivates the following approach is that certain subsets
of tables are not particularly helpful to consider. Specifically, even if we were
to propose materialized views on those table subsets, the resulting configu-
ration would be only slightly more efficient. This can happen because the
table subsets occur either infrequently in the workload or only in inexpensive
queries. For instance, consider a workload of 100 queries whose total ...