Access Methods for Multiversion Data

时间分割B树是一种数据检索系统，它利用了两种存储介质的优点：廉价、坚固、不可擦除但访问速度慢的光盘存储和更昂贵但访问更快的磁盘存储。这是通过将最新版本的数据放置在磁盘上，在磁盘上可以快速更新，并在较慢的光盘成熟时增量地将较旧的数据移动到较慢的光盘上来实现的。此外，保留所有版本的数据取代了日志，并使恢复变得简单。首席调查员计划通过以下方式分析、改进和扩展时间分裂B-树：对两种介质上的空间利用进行参数化，以提高预期使用模式的性能；提供对几种时间语义的支持；与其他建议的使用这两种介质的方法进行比较；为大型分层版本对象提供支持；允许丢弃记录的中间版本；当旧版本迁移到光盘时，对当前(磁盘)数据进行合并。该研究将有助于理解访问方法、事务处理、时态语义、版本控制之间的相互作用以及不同特性的存储介质之间的相互作用。

The Time-Split B-tree is a system of data retrieval which takes advantage of the best aspects of two storage mediums: cheap, sturdy, non-erasable, but slow-access optical disk storage and more expensive but faster-access magnetic disk storage. This is accomplished by placing recent versions of data on magnetic disk where it can be updated quickly and incrementally moving older data to the slower optical disk as it matures. In addition, keeping all versions of data takes the place of a log and makes recovery simple. The principal investigator plans to analyze, refine and extend the Time-Split B-tree by: parameterizing space utilization on both mediums to improve performance for an expected use pattern; providing support for several kinds of temporal semantics; comparing with other proposed methods for using both mediums; providing support for large hierarchical versioned objects; allowing intermediate versions of records to be discarded; and, consolidating current (magnetic disk) data when old versions are migrated to optical disk. The research will contribute to the understanding of the interaction between access methods, transaction processing, temporal semantics, versioning and the interplay of storage mediums with different characteristics.