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標題: 物件導向資料庫系統之暫存區管理
Buffer Management for Object-oriented Database Management Systems
作者: 陳世穎
Chen, Shi-Ying
關鍵字: Buffer Management
Object-oriented Database Management System
Query Management
出版社: 資訊科學研究所
摘要: 暫存區管理是改善資料庫系統效能的一種重要技巧,透過把資料暫存在主記憶體內,以減少磁碟存取資料的次數。這種技巧原來是用在作業系統之主記憶體管理,後來也被用於關連式資料庫系統上。然而隨著物件導向資料庫系統的逐漸流行,研究者亦開始探討物件導向資料庫系統暫存區管理的問題。在物件導向資料庫系統中,影響其效能的一個重要因素,就是使用物件指標來取得分散在磁碟各處的物件。本文中,我們將建立一數學模式,討論物件導向資料庫系統中,暫存區數目控制及取代的策略。這個模式是根據最常見三種查詢方工(結合,巡戈搜尋,等值)的各種查詢處理演算法之成本分析所導出的。這個數學模式涵蓋了物件組成架構(繼承關係和組合關係)和索引技巧;分析的結果將以圖表表示。我們亦提出此模式在資上的應用,這個模式付單獨應用在暫存區管理上或是結合暫存區管理及查詢管理而應用。
Buffer management is an important technique to improve system performance. It reduces the disk I/O cost by caching data in main memory buffers. The technique was originally developed for the main memory management in operating systems and later used in relational database management systems. With the increasing popularity of object-oriented database systems (OODBMS), researchers start to look into the buffer management issue in OODBMS. One big performance penalty of OODBMS is due to pointer chasing using OID (object ID) to reference objects which may scatter around disk pages. In this thesis, we present a cost model to study both the allocation policy and the replacement policy for the buffer management in OODBMS. The model is derived from the cost formulae of disk accesses for various algorithms to evaluate the three most common types of object access queries, i.e., join, navigational search, and value equality. The cost formulae also take account of object structures (i.e., class hierarchy and class composition hierarchy and indexing techniques. Illustration results of our analysis are shown in this thesis. The applications of this model are also presented. This model can be either directly applied to the buffer management or used to integrate both the buffer management and the query management in OODBMS.
Appears in Collections:資訊科學與工程學系所



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