视图增量的同步计算方法

Synchronous Algorithm of Computing View Increment

为有效降低视图增量计算的代价,提出了净化操作和主外码约束的优化同步计算方法.数据源基表的更新操作可能对同一元组多次反复的修改,而在视图增量的维护中并不需要反映基表的整个更新过程,而只是维护某个时间的状态一致,因而利用净化操作减少了计算的数据量.数据源基表间的主外码约束使得部分增量子查询的结果为空,减少这样的增量子查询提高了计算的效率.实验分析表明优化后的同步计算方法有效地降低了计算和维护代价.

In order to reduce effectively the cost of view increment computation,we proposed the algorithm of synchronous computation which is optimized by the net change of increment and primary-foreign key constraints.Some tuples of base table in data source are modified over and over again,but the whole change process is not needed to reflect in the materialized views.So the net change can reduce the amount of data to calculate.And some increment sub-query of materialized views is empty because of the primary-foreign key constraints which caused to reduce query computation.The analysis of result showed that the optimized synchronization method could reduce the computation and maintenance cost effectively.