Journal ArticleDOI
The Lorel Query Language for Semistructured Data
Reads0
Chats0
TLDR
The main novelties of the Lorel language are the extensive use of coercion to relieve the user from the strict typing of OQL, which is inappropriate for semistructured data; and powerful path expressions, which permit a flexible form of declarative navigational access and are particularly suitable when the details of the structure are not known to the user.Abstract:
language, designed for querying semistructured data. Semistructured data is becoming more and more prevalent, e.g., in structured documents such as HTML and when performing simple integration of data from multiple sources. Traditional data models and query languages are inappropriate, since semistructured data often is irregular: some data is missing, similar concepts are represented using different types, heterogeneous sets are present, or object structure is not fully known. Lorel is a user-friendly language in the SQL/OQL style for querying such data effectively. For wide applicability, the simple object model underlying Lorel can be viewed as an extension of the ODMG data model and the Lorel language as an extension of OQL. The main novelties of the Lorel language are: (i) the extensive use of coercion to relieve the user from the strict typing of OQL, which is inappropriate for semistructured data; and (ii) powerful path expressions, which permit a flexible form of declarative navigational access and are particularly suitable when the details of the structure are not known to the user. Lorel also includes a declarative update language. Lorel is implemented as the query language of the Lore prototype database management system at Stanford. Information about Lore can be found at http://www-db.stanford.edu/lore. In addition to presenting the Lorel language in full, this paper briefly describes the Lore system and query processor. We also briefly discuss a second implementation of Lorel on top of a conventional object-oriented database management system, the O2 system.read more
Citations
More filters
Journal ArticleDOI
Representation of Web Data in A Web Warehouse
TL;DR: This paper focuses on how to represent and store relevant hyperlinked Web documents effectively in a Web warehouse called WHOWEDA (WareHouse Of WEb DAta) for further querying and manipulation.
Journal ArticleDOI
Modeling views in the layered view model for XML using UML
TL;DR: A Layered View Model (LVM) for XML with conceptual and schemata extensions is proposed, allowing analysis and design of views to be separated from their implementation, and a view transformation methodology for XML views in the LVM is defined.
Journal ArticleDOI
Retrieval of multimedia web documents and removal of redundant information
TL;DR: A search engine for multimedia web documents and a methodology for removing (partially or totally) redundant information from multiple documents in an effort to synthesize new documents are described.
Proceedings Article
Infrastructure of the subject mediating environment aiming at semantic interoperability of heterogeneous digital library collections
TL;DR: A required infrastructure of the subject mediators aiming at semantic interoperability of heterogeneous digital library collections is presented and the diversity of information models that should be uniformly represented at the canonical level is analyzed.
Proceedings ArticleDOI
Querying semi-structured data with graph grammars
TL;DR: This paper proposes a new form of queries, called graph queries, whose answers are (marked) graphs having a particular structure, extracted from the source graph, and shows that a simple form of graph grammar can be profitably used to define graph queries.
References
More filters
Journal ArticleDOI
Query evaluation techniques for large databases
TL;DR: This survey describes a wide array of practical query evaluation techniques for both relational and postrelational database systems, including iterative execution of complex query evaluation plans, the duality of sort- and hash-based set-matching algorithms, types of parallel query execution and their implementation, and special operators for emerging database application domains.
Book
The object database standard: ODMG 2.0
R. G. G. Cattell,Douglas K. Barry,Dirk Bartels,Mark Berler,Jeff Eastman,Sophie Gamerman,David Jordan,Adam Springer,Henry Strickland,Drew Wade +9 more
TL;DR: With this book, standards are defined for object management systems and this will be the foundational book for object-oriented database product.
Proceedings ArticleDOI
Object exchange across heterogeneous information sources
TL;DR: An object-based information exchange model and a corresponding query language are defined that are well suited for integration of diverse information sources and used to integrate heterogeneous bibliographic information sources.
Book ChapterDOI
Querying Semi-Structured Data
TL;DR: The main purpose of the paper is to isolate the essential aspects of semistructured data, and survey some proposals of models and query languages for semi-structured data.