In semistructured databases there is no schema fixed in advance. To provide the benefits of a schema in such environments, we introduce DataGuides: concise and accurate structural summaries of semistructured databases. DataGuides serve as dynamic schemas, generated from the database; they are useful for browsing database structure, formulating queries, storing information such as statistics and sample values, and enabling query optimization. This paper presents the theoretical foundations of DataGuides along with an algorithm for their creation and an overview of incremental maintenance. We provide performance results based on our implementation of DataGuides in the Lore DBMS for semistructured data. We also describe the use of DataGuides in Lore, both in the user interface to enable structure browsing and query formulation, and as a means of guiding the query processor and optimizing query execution.

This paper describes the design and implementation of PESTO (Portable Explorer of STructured Objects), a user interface that supports browsing and querying of object databases. PESTO allows users to navigate the relationships that exist among objects. In addition, users can formulate complex object queries through an integrated query paradigm ("query-in-place") that presents querying as a natural extension of browsing. PESTO is designed to be portable to any object database system that supports a high-level query language; in addition, PESTO is extensible, providing hooks for specialized predicate formation and object display tools for new data types (e.g., images or text). 1 Introduction The Garlic project at the IBM Almaden Research Center [Care95] is developing a system and associated tools for managing large quantities of heterogeneous multimedia information. The goal of Garlic is to permit both traditional and multimedia data residing in a variety of existing data repositories ...

Today's enterprises typically employ multiple information systems, which are independently developed, locally administered, and different in logical or physical designs. Therefore, a fundamental challenge in enterprise information management is the sharing of information for enterprise users across organizational boundaries; which requires a global query system capable of providing on-line intelligent assistance to users. Conventional technologies, such as schema-based query languages and hard-coded schema integration are not sufficient to solve this problem. This research develops a new approach, "model-assisted global query system, " that utilizes an on-line repository of enterprise metadata- the metadatabase- to facilitate global query formulation and processing with certain desirable properties such as adaptiveness and open systems architecture. A definitional model characterizing the various classes and roles of the minimally required metadata as knowledge for the system is

Abstract. The extended NF 2 (eNF 2) data model permits structured data values like (sub-)relations, lists and tuples to be included as attributes in relations. While it is a very powerful data model, it is not easy to handle and even harder to implement. In

I authorize the University of Waterloo to lend this thesis to other institutions or individuals for the purpose of scholarly research. I further authorize the University of Waterloo to reproduce this thesis by photocopying or by other means, in total or in part, at the request of other institutions or individuals for the purpose of scholarly research. iii The University of Waterloo requires the signatures of all persons using or photocopying this thesis. Please sign below, and give address and date. Functional dependency analysis can be applied to various problems in query optimization: selectivity estimation, estimation of (intermediate) result sizes, order optimization (in particular sort avoidance), cost estimation, and various problems in the area of semantic query optimization. Dependency analysis in an ansi sql relational model, however, is made complex due to the existence of null values, three-valued logic, outer joins, and duplicate rows. In this thesis we define the notions of strict and lax functional dependencies, strict and lax equivalence constraints, and null constraints, which capture both a

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Graphical user interfaces have become very popular for database systems since they increase the usability of these applications. The functionality and ease- of-use of the graphical user interface, however, depend on the expressiveness and complexity of the underlying data model. With the advent of new database technology based on powerful data models like the object-oriented data model new challenges and new opportunities are posed in user interface design. In this paper we discuss critical issues of graphical user interface development for object-oriented database systems. 1 Introduction We are witnessing a change of attitude concerning the importance of the user interface of an application compared to the application itself. As Dertouzous pointed out in his plenary address at CHI'90 [18], nowadays, about 70% of an application's code is devoted to user interface handling, and only 30% deals with the actual application. With the advent of powerful bit-mapped graphic workstations and in...

In semistructured databases there is no schema fixed in advance. To provide the benefits of a schema in such environments, we introduce DataGuides: concise and accurate structural summaries of semistructured databases. DataGuides serve as dynamic schemas, generated from the database; they are useful for browsing database structure, formulating queries, storing information such as statistics and sample values, and enabling query optimization. This paper presents the theoretical foundations of DataGuides along with an algorithm for their creation and an overview of incremental maintenance. We provide performance results based on our implementation of DataGuides in the Lore DBMS for semistructured data. We also describe the use of DataGuides in Lore, both in the user interface to enable structure browsing and query formulation, and as a means of guiding the query processor and optimizing query execution.

magantyQinformix.com This paper describes the design and implementation of PEST0 (Portable Explorer of Snuctured Objects), a user interface that supports browsing and querying of object databases. PEST0 allows users to navigate the relationships that exist among objects. In addition, users can formulate complex object queries through an integrated query paradigm (“query-in-place”) that presents querying as a natural extension of browsing. PEST0 is designed to be portable to any object database system that supports a high-level query language; in addition, PEST0 is extensible, providing hooks for specialized predicate formation and object display tools for new data types (e.g., images or text).