A Design of an Experiment to Model Data Base System Performance

A statistical design of an experiment for modeling the performance (access time) of a data base (DB) system in a controlled environment has been outlined. A three-factor pilot experiment with retrieval sequence, logical view (combined with access method), and target segment type as factors was designed and the results analyzed for a specific IMS batch DB. It was found that: 1) the variation of sequences of DB retrieval calls in the application program did not have any signifilcant effect on the access time, whereas the other two factors did have significant effect; 2) the variability in access time is not completely explained by these three factors; and 3) the distribution of the residual error is "nonnormal," with a large positive skew.