Safely and Efficiently Updating References During On-line Reorganization

With today’s demands for continuous availability of mission-critical databases, on-line reorganization is a necessity. In this paper we present a new on-Iine reorganization algorithm which defers secondary index updates and piggybacks them with user transactions. In addition to the significant reduction of the total I/O cost, the algorithm also assures that almost all the database is available all of the time and that the reorganization is interruptible and restartable. We believe that the technique presented in this paper could be used for improving normal database update performance as well.