Incremental Recomputation of Active Relational Expressions
Incremental Recomputation of Active Relational Expressions
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DOI：
10.1109/69.91063
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发表时间：
1991-09
期刊：
影响因子：
--
通讯作者：
Xiaolei Qian;G. Wiederhold
中科院分区：
文献类型：
--
作者：
Xiaolei Qian;G. Wiederhold
与数据库内容相比，数据库更新量小且是增量式的。因此，希望对活动关系表达式（例如视图、派生数据、完整性约束、活动查询和监视器）的重新计算也能增量式地进行。提出了一种基于有限差分技术的活动关系表达式增量重新计算的高效算法。数据库更新被建模为对数据库关系的增量式变化，并且该算法通过更新传播推导出需要重新计算的最小增量关系表达式。该算法在物化视图和派生数据的维护、完整性约束的检查以及活动查询和监视器的评估中具有应用。
Database updates are small and incremental compared to database contents. It is therefore desirable that recomputations of active relational expressions-such as views, derived data, integrity constraints, active queries, and monitors-can also be performed incrementally. An efficient algorithm for the incremental recomputation of active relational expressions based on finite differencing techniques is presented. Database updates are modeled as incremental changes to database relations, and the algorithm derives, by update propagation, the minimal incremental relational expressions that need recomputation. The algorithm has applications in the maintenance of materialized views and derived data, the checking of integrity constraints, and the evaluation of active queries and monitors. >