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Schemes of Storing XML Query Cache

Schemes of Storing XML Query Cache. Dong Jin Lee Yun-young Lee Fan Zhang. What is the motivation for the work?.

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Schemes of Storing XML Query Cache

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  1. Schemes of Storing XML Query Cache Dong Jin Lee Yun-young Lee Fan Zhang

  2. What is the motivation for the work? • Although XML query caching for XML database-backed Web applications began to be investigated recently, the issue of how the cached query results are stored has not been addressed despite its practical significance.

  3. What was the aim of the work? • To devise the best scheme that well compromises between the two major operations on a cached query result, as there exist performance tradeoffs between the operations. • Retrieving • Updating

  4. The schemes implemented and tested • Schemes based on plain text file • Text/DOM (TD) • Indexed Text (ITD) • Indexed Log-structured Text (ILT) • Schemes based on PDOM file • PDOM (PD) • Indexed PDOM (IPD) • PDOM Fragments (PDF) • PDOM/Text Fragments (PDTF) • A scheme based on RDB • RDB (RDB)

  5. How did the authors prove the findings?What method did they use? • They evaluated the performance of updating the cache document and that of returning the query result. • They also measured the overhead of each scheme in terms of the time and the space it takes for storing the cache document.

  6. What are the key findings? • Schemes TD and IT are infeasible in updating the cached query result for its incremental refresh because they manipulate entire cache document in order to update just a small portion of the document. • Schemes RDB and PDF are infeasible in returning the cached query result because they need to do much work in order to put the decomposed parts of the cache document together. Scheme PDTF is feasible though due to maintenance of the text fragment files. • Schemes PDTF, PDF, and RDB take much time in initially storing the cached query result compared to other schemes because they employ the decomposed storage format. • The PDOM file-based schemes except PDTF are most efficient in space utilization in storing the cached query results. • Scheme ILT is most feasible in both updating the cached query result for its incremental refresh and returning the cached query result. Scheme IPD is not so good as ILT but feasible in both operations. So is PDTF though it is inefficient in storing the cached query result.

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