1. A database design tuning system comprising the following computer-implemented components: at least one processor that executes the following computer executable components stored on a computer readable medium; an interface component that acquires a database schema; and a logical tuner component that automatically employs one or more schema transformations to optimize the database schema for performance with respect to a workload, wherein the logical tuner component identifies the one or more schema transformations that minimize workload evaluation cost, and are reversible, non-redundant and normalization preserving, the one or more schema transformations comprising a mapping table transformation that maps wide attributes with small domains to respective narrower attributes in at least one table, wherein the narrower attributes and associated mapping utilize less bytes of data than the wide attributes to facilitate reduction in width of the at least one table and the bytes of data utilized, the respective narrower attributes comprising respective integer values, and respective data values of the wide attributes are replaced with the respective integer values in the at least one table as part of the mapping, wherein the respective integer values are respectively associated with the respective data values of the wide attributes in the mapping, and wherein a query is automatically rewritten in accordance with the mapping, and wherein the one or more schema transformations further comprising a schema transformation that partitions out one or more columns from a table including frequent values, removes the frequent values from the one or more partitioned columns and stores the frequent values separately to exploit data distribution skew.