Expiring Data in a Warehouse
Héctor García-Molina, Wilburt Juan Labio, Jun Yang · 1998
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 modi#cations are expected from external sources. The latter can signi#cantly increase the amountof data that can be expired. We present e#- cient 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. 1 Introduction Materialized views are often used to store warehouse data. The amount of data copied into these views maybevery large; for instance, #JMS95# cites a major telecommunications company that collects 75GB of detailed call data every day or 27TB a year. Even with cheap d...