Abstract-All methods for efficient integrity checking require all integrity constraints to be totally satisfied, before any update is executed. However, a certain amount of inconsistency is the rule, rather than the exception in databases. In this paper, we close the gap between theory and practice of integrity checking, i.e., between the unrealistic theoretical requirement of total integrity and the practical need for inconsistency tolerance, which we define for integrity checking methods. We show that most of them can still be used to check whether updates preserve integrity, even if the current state is inconsistent. Inconsistency-tolerant integrity checking proves beneficial both for integrity preservation and query answering. Also, we show that it is useful for view updating, repairs, schema evolution and other applications.

Integrity maintenance methods have been definedfor preventing Updates from

Database replication protocols need to detect, block or abort part of conflicting transactions. A possible solution is to check their writesets (and also their readsets in case a serialisable isolation level is requested), which however burdens the consumption of CPU time. This gets even worse when the replication support is provided by a middleware, since there is no direct DBMS support in that layer. We propose and discuss the use of the concurrency control support of the local DBMS for detecting conflicts between local transactions and writesets of remote transactions. This allows to simplify many database replication protocols and to enhance their performance.

No abstract

No abstract