Partial rollback in object-oriented/object-relational database management systems with dual buffer

摘要

Partial rollback mechanism has been widely supported by many database management systems (DBMSs). It allows a transaction to be rolled back partially, that is, only back to a certain savepoint set by the user. A partial rollback, however, makes the DBMS buffer management complicated because it requires the DBMS to restore the state of not only the database but also the buffers. There are several literatures addressing such a partial rollback in a relational DBMS (RDBMS), which has page buffer only. However, to our knowledge, there exists no literature addressing it in an object-oriented/relational DBMS (OO/ORDBMS). The RDBMS partial rollback scheme cannot be applied to OO/ORDBMSs directly. The reason is that, unlike RDBMSs, many OO/ORDBMSs use dual buffer which consists of object buffer and page buffer. In this paper, we thoroughly study the partial rollback schemes for OO/ORDBMSs with dual buffer. For this, we propose four different partial rollback schemes which are based on (single) page buffer, (single) object buffer, dual buffer using a soft log, and dual buffer using shadows, respectively. The schemes proposed are practical enough to be implemented in a real OO/ORDBMS. The results of performance evaluations show that the dual buffer-based scheme using shadows achieves the best performance.