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Publications (2)0 Total impact

  • Article: Unknown
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    ABSTRACT: this paper, we propose a newisol0W37 lo el navigN stability. First, weanalj6 the data access patterns of navigational applionalR7 define a navigational model based on the access patterns, and propose navigation stabil] y by extending thel cking protocol of cursorstabil7 y based on the model Second, we show that navigation stabiln ysol es those inconsistency problfi6 of cursorstabil0 y in ORDBMSs. Last, through extensive simul]0W7W we show that navigation stabilo y improves the concurrency significantl compared withlt el 3
    04/2002;
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    ABSTRACT: SUMMARY In order to enhance the performance, many database management systems (DBMSs) execute transactions at isolation level 2rather than at isolation level 3, the strict two phase locking, even if it sacrifices consistency to a certain de- gree. Cursor stability, a variant of isolation level 2in relational DBMSs (RDBMSs), has been widely used as a useful technique for obtaining concurrency achievable at level 2without much sac- rificing consistency. However, cursor stability is much less usable in object-relational DBMSs (ORDBMSs) because navigational applications in ORDBMSs can suffer from critical inconsistency problems such as dangling pointers, lost updates, and reading in- consistent complex objects. In this paper, we propose a new iso- lation level, navigation stability, that prevents the inconsistency problems of cursor stability for navigational applications, while avoiding significant degradation of the concurrency of level 3. First, we analyze the inconsistency problems of cursor stability for navigational applications. Second, we define navigation sta- bility as an extension of cursor stability and show that it solves those inconsistency problems of cursor stability in ORDBMSs. Third, through extensive simulation, we show that navigation stability significantly enhances the performance compared with level 3. For workloads consisting of transactions of long duration, compared with level 3, the throughput of navigation stability is enhanced by up to 200%; the average response time reduced by as much as 55%; and the abort ratio reduced by as much as 77%. From these results, we conclude that navigation stability is a useful isolation level in ORDBMSs that can be used in place of isolation level 3 to improve the performance and concurrency
    01/2001;