Principles of Transaction-Based On-Line Reorganization

Abstract

For very large databases such as those used by banks and airlines, cost considerations may forbid shutting down the service for a long period of time and reorganizing off-line. Similarly, the size of the database may preclude constructing another copy with the desired organization on another disk collection. Such databases need incremental on-line reorganization. References to records occur in many places in the database. If the identifier used for the record changes due to reorganization, all of these references must be changed. This paper concentrates on the problems of updating references to enable on-line parallel incremental reorganization to be correct while reusing existing code and making minimal changes to underlying transaction processing software. 1 Introduction In many large database installations, down time of only a few minutes can cause a loss of millions of dollars. Yet currently, the only way to reorganize the database is to shut it down and spend hours or days recon...