A recovery method supporting user-interactive undo in database management systems

Abstract

User-interactive undo is a kind of recovery facility that allows users to correct mistakes easily by canceling and reexecuting operations that have already been executed. Supporting user-interactive undo is essential for authoring processes in new database applications such as software engineering, hypermedia, and computer-aided design. A partial rollback using savepoints supported by commercial database management systems (DBMSs), which allows only cancellation of executed operations, is a restricted form of user-interactive undo. Although many applications use DBMSs, they have to provide user-interactive undo by themselves due to lack of support from the DBMSs. Since implementation of user-interactive undo is quite complex, it poses significant burden to application programmers. This paper proposes a new recovery method facilitating user-interactive undo in DBMSs. Such a facility relieves the programmers of implementing user-interactive undo themselves in developing DBMS applications. The method guarantees fast rollback of transactions that contain user-interactive undos. It also provides users with the bulk undo operation that restores the database to a predetermined point in the past. The bulk undo operation resembles partial rollback, but differs in that it allows redo that cancels the bulk undo. Moreover, the performance of the method is comparable to that of the traditional recovery method in spite of added functionalities. (C) 1999 Elsevier Science Inc. All rights reserved.