Association rule mining often generates a huge number of rules, but a majority of them either are redundant or do not reflect the true correlation relationship among data objects. We re-examine this problem and show that two interesting measures, all-confidence (denoted as /spl alpha/) and coherence (denoted as /spl gamma/), both disclose genuine correlation relationships and can be computed efficiently. Moreover, we propose two interesting algorithms, CoMine(/spl alpha/) and CoMine(/spl gamma/), based on extensions of a pattern-growth methodology. Our performance study shows that the CoMine algorithms have high performance in comparison with their Apriori-based counterpart algorithms.

In a database management system (DBMS), partial rollback is an important mechanism for canceling only part of the operations executed in a transaction back to a savepoint. Partial rollback complicates buffer management because it should restore the state of the buffers as well as that of the database. Several relational DBMSs (RDBMSs) currently provide this mechanism using page buffers. However, object-oriented or object-relational DBMSs (OO/ORDBMSs) cannot utilize the partial rollback scheme of RDBMSs as is because, unlike RDBMSs, many of them use a dual buffer consisting of an object buffer and a page buffer. In this paper, we propose a thorough study of partial rollback schemes of OO/ORDBMSs with a dual buffer. First, we classify the partial rollback schemes of OO/ORDBMSs into a single buffer-based scheme and a dual buffer-based scheme by the number of buffers used to process rollback. Next, we propose four alternative partial rollback schemes: a page buffer-based scheme, an object buffer-based scheme, a dual buffer-based scheme using a soft log, and a dual buffer-based scheme using shadows. We then evaluate their performance through simulations. The results show that the dual buffer-based partial rollback scheme using shadows provides the best performance. Partial rollback in OO/ORDBMS has not been addressed in the literature; yet, it is a useful mechanism that must be implemented. The proposed schemes are practical ones that can be implemented in such DBMSs.