On-line reorganization in object databases
On-line reorganization in object databases
复制标题
对象数据库的在线重组
DOI：
10.1145/342009.335381
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
S. Sudarshan
中科院分区：
文献类型：
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作者：
M. K. Lakhamraju;R. Rastogi;S. Seshadri;S. Sudarshan
对象数据库中对象的重组是压缩、聚类和模式演化等操作的重要组成部分。某些应用程序域的高可用性要求（24 × 7操作）要求在对并发执行事务的干扰最小的情况下在线执行重组。
在本文中，我们解决了对象数据库中的在线重组问题，其中一组对象必须从一个位置迁移到另一个位置。具体来说，我们考虑的情况下，在数据库中的对象可能包含物理引用到其他对象。在这种情况下，重新定位一个对象需要找到引用它的对象集（父对象），并修改每个父对象中的引用。我们提出了一个算法称为增量重组算法（伊拉），实现了上述任务，以最小的干扰并发执行的事务。伊拉算法在任何时间点最多锁定两个不同的对象。我们已经在IIT Bombay开发的存储管理器Brahma上实现了伊拉，并进行了广泛的性能研究。我们的实验表明，伊拉使在线重组可行，并发执行的事务的响应时间和整体系统吞吐量的影响很小。我们还描述了如何伊拉算法可以处理系统故障。
Reorganization of objects in an object databases is an important component of several operations like compaction, clustering, and schema evolution. The high availability requirements (24 × 7 operation) of certain application domains requires reorganization to be performed on-line with minimal interference to concurrently executing transactions.
In this paper, we address the problem of on-line reorganization in object databases, where a set of objects have to be migrated from one location to another. Specifically, we consider the case where objects in the database may contain physical references to other objects. Relocating an object in this case involves finding the set of objects (parents) that refer to it, and modifying the references in each parent. We propose an algorithm called the Incremental Reorganization Algorithm (IRA) that achieves the above task with minimal interference to concurrently executing transactions. The IRA algorithm holds locks on at most two distinct objects at any point of time. We have implemented IRA on Brahma, a storage manager developed at IIT Bombay, and conducted an extensive performance study. Our experiments reveal that IRA makes on-line reorganization feasible, with very little impact on the response times of concurrently executing transactions and on overall system throughput. We also describe how the IRA algorithm can handle system failures.