1. One or more storage media storing instructions which, when executed by one or more computing devices, cause performance of: sending a first data-to-dataset mapping to one or more mid-tier servers that provide connections to database servers; receiving information that indicates at least one of a change to a pattern of data access or a demand for data; using the information to automatically generate a second data-to-dataset mapping that is different from the first data-to-dataset mapping; and sending the second data-to-dataset mapping to the one or more mid-tier servers.