clifto07

Abstract
Schema integration is an important discipline for constructing a heterogeneous database system, since there exist various semantic discrepancies among local schemas. However, prior works rarely address the problems of integrating local relations with conflicts of different schema structures. In this paper, we propose an approach for the integration of local relations with such conflicts. In our approach, we define some auxiliary data called metadata for local schemas. The relations can be classified into some classes according to the metadata. The local relations with conflicts of different schema structures are respectively transformed to new relations with the same structure.

摘 要
綱要整合是建構異質資料庫系統的重要學科，因為局部綱要間存有各種語意不一致性。然而，先前工作極少訴求其與不同綱要結構之衝突，進行局部關係整合的問題。在本論文中，我們擬議一種與這類衝突進行局部關係整合的途徑。在我們的途徑中，我們為局部綱要界定一些稱為後設資料的輔助資料。這些關係，可以依據後設資料劃分為若干種類。與不同綱要結構衝突之局部關係，則分別轉換為與相同結構之新關係。

Finally, we integrate these new relations. We also explore the query decomposition process for global queries. A global query is decomposed into many local queries according to the local schemas' structures. The results of the local queries will be sent to the global site. Finally, the global site integrates the local results into a new one and poses the global query on the integrated result again to get the final result. Since this process filters out unnecessary data in each local site, it can also be regarded as an important work for global query optimization.
最後，我們整合這些新關係。我們也探討全局查詢的查詢分解過程。全局查詢依據局部綱要之結構，分解成為眾多局部查詢。局部查詢之結果，將予送至全局站點。終而，全局站點整合局部結果成為新站點，並再度對所整合結果提出全局查詢，以取得最後結果。由於此一過程已將各局部站點中之非必要資料予以濾除，故亦可視為全局查詢最佳化之一重要工作。

Keywords (關鍵詞): Heterogeneous database systems (異質資料庫系統); Schema integration (綱要整合); Metadata (後設資料); Query decomposition (查詢分解); Global query optimization (全局查詢最佳化)