Abstract: This paper focuses on requirements of multi-version management in What-if analysis. Multi-version update policy is presented in main-memory OLAP system with What-if analysis support based on different hypothetical update techniques which includes traditional cascade multi-version update and multi-version update based on difference value delta tuples. Delta tuple pre-merge mechanism is proposed to improve the performance of cascade hypothetical version merging procedure. Performance experiment shows that the pre-merge hypothetical update can reduce both time cost of multi-version updates and total time cost of What-if queries remarkably compared with cascade multi-version update.

Key words: What-if analysis, hypothetical update, hypothetical update data view, cascade hypothetical update

摘要： 针对What-if分析中的多版本更新管理需求，根据不同的假设更新实现技术，提出支持What-if分析的内存OLAP系统中的多版本更新策略，其中包括常规的递归假设更新和基于差值的多版本假设更新，采用预合并机制的delta记录合并算法来提高级联假设更新模式下的多版本What-if查询性能。实验表明，与常规的递归假设更新相比，该算法无论在减少多版本更新代价方面还是在减少整体What-if查询时间方面均有效。

关键词: What-if分析, 假设更新, 假设更新数据视图, 级联假设更新

CLC Number: 

• TP301.6