Journal ArticleDOI
The Lorel Query Language for Semistructured Data
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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
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Journal ArticleDOI
Schemas for web data: a reverse engineering approach
TL;DR: This paper shows how to generate schemas of a set of HTML or XML documents retrieved from the web in the context of the web warehousing system called W howeda, and discusses the formal algorithm for generating aset of simple web schemas from a coupling query.
Proceedings ArticleDOI
Integration of semistructured data with partial and inconsistent information
TL;DR: This paper redefine the notion of semistructured objects to reflect the existence of partial and inconsistent information and proposes a new integration operator for this purpose and discusses its semantic properties.
Semantic caching for xml queries
Elke A. Rundensteiner,Li Chen +1 more
TL;DR: This dissertation addresses two issues fundamental to building an XQuery-based semantic caching system: XQuery containment and rewriting, and an effective replacement strategy based on the detailed user access statistics recorded on the internal XML view structure.
Book ChapterDOI
Accommodating Changes in Semistructured Databases Using Multidimensional OEM
TL;DR: This paper explains in detail how MOEM can represent the history of OEM databases, and discusses howMOEM properties are applied in the case of representing OEM histories, and shows that temporal OEM snapshots can be obtained from MOEM.
References
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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.