Definition

• traditional view update problem and why this one is different and more difficult
• As the database changes because of updates applied to the base relations, the materialized views may also require change. A materialized view can always be brought up to date by re-evaluating the view definition. However, complete re-evaluation is wasteful.
  "heuristic of inertia"- only a part of the view changes in response to changes in the base relations
• steps of view maintenance:
  • propagation (computing changes to the view)
  • refreshing (applying changes to the mat. view)