Data warehouses collect data into materialized views for analysis.
After some time, some of the data may no longer be needed or may not
be of interest.  In this paper, we handle this by expiring or
removing unneeded materialized view tuples.  A framework supporting
such expiration is presented.  Within it, a user or administrator can
declaratively request expirations and can specify what type of
modifications are expected from external sources.  The latter can
significantly increase the amount of data that can be
expired.  We present efficient algorithms for determining what data can
be expired (data not needed for maintenance of other views),
taking into account the types of updates that may occur.