1. A method of managing statistical views in a database system, the method comprising: collecting data relating to optimization and execution of a workload in the database system, the workload comprising a plurality of sub-expressions for which data relating to optimization and execution of the workload is collected; and automatically generating, for a subset of the plurality of sub-expressions less than a total number of sub-expressions in the workload, a set of one or more statistical views based on the collected optimization and execution data, each of the one or more statistical views corresponding to one of the sub-expressions in the subset of the plurality of sub-expressions, wherein the number of statistical views generated is less than the total number of sub-expressions in the workload for which data relating to optimization and execution of the workload is collected.