Describe why database redesign is necessary?

Database redesign involves the redesign of an existing database to make room for required changes or to make other improvements to the database performance. There is no guarantee that a database will be 100% correct once designed and developed the first time. Therefore a redesign may be carried out to rectify any errors and/or short comings. When an information system is installed the behavior of the users change over the time when they interact with the new information system. Database redesign may also be required to accommodate this changing behavior.