One of the first tasks in developing a test plan is to come up with a test schedule. Most product development methodologies contain metrics for producing time estimates for testing as well as development. From experience, these metrics fall well short of the requirements for testing a data warehouse application. The shortcomings of these metrics are due to the size and complexity of data warehouse systems. For example, a simple problem with a large query can cause it to run inefficiently. However, because of the size of the query it may take a day to shew that it is not going to complete in the desired time-scales. By the time the query has been tuned and re-run several times, many days of testing time may have been lost.