METHOD AND APPARATUS FOR RESTORING DATA IN A COMPUTING SYSTEM

摘要

Method and apparatus for assuring atomicity of user requested multi-row update operations to tables such as in a relation database (24), guaranteeing that for any update operation that succeeds all stated effects will have occurred and that for any update operation that fails the system state as perceived by the user remains unchaged. This is accomplished by establishing, in response to a multi-row update operation request, an execution module containing machine language code instructions implementing the update operation request with a savepoint request at the beginning of the execution module. For each set of instruction in or called by the execution module which modified the user perceived system state, undo information is logged to a soft log (20). Upon completing the execution module, the savepoint is dropped, causing all soft log information recorded since the savepoint to be deleted and releasing all resources held to guarantee restoration of the user perceived system state at the time of the savepoint request. Responsive to the detection of an error during execution of the module, the soft logged undo information is used to restore the user perceived state to that existing at the time of the savepoint request.