Managing data obsolescence in relational databases

Abstract

Data obsolescence is managed using a bitmap or bit array index which is associated with a table during an obsolescence control period. A table is selected to undergo obsolescence control for a period of time. Any records that have not been accessed for a certain number of cycles 'M', which represents an obsolescence limit, are deemed to be obsolete. During at least a part of each cycle, the results of database queries to the table are monitored, such that for each cycle an 'obsolescence' bitmap is created indicating which records were accessed. Once a sufficient number of cycles have elapsed, so that records that have not been accessed at all since the start of the obsolescence control period lie outside the obsolescence limit, queries are restricted to records which have been accessed during the last ‘M’ cycles by applying the ‘M’ most recently stored obsolescence bitmaps.