Gustav Fahl and Tore Risch. Query Processing Over Object Views of Relational Data. VLDB Journal, 6(4):261--281, 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... of a number of types (classes) and functions (methods, attributes) Unlike regular OO systems the extents of these types and functions are not explicitly stored in a database but are derived, through an OO multidatabase query language, from data in the underlying data sources and other mediators [20, 21, 19]. We use the term multidatabase view or function when a view or function is defined in terms of views, types and functions defined in other mediators. An example of a mediator composition is shown on Fig. 1. In this example, applications access data stored in several data sources through a ....

Fahl, G., Risch, T.: Query processing over object views of relational data. VLDB Journal 6 (1997) 261-281

....over the Internet using an internal TCP IP socket based protocol. This protocol is used only for inter AMOS II communication while wrappers interface the data sources, such as, e.g. wrappers for accessing XML data sources through HTTP [2] and for accessing relational databases through ODBC [3,4]. Each mediator server is also a DBMS of its own containing all the traditional database facilities, such as a storage manager, a recovery manager, a transaction manager, a disk backup manager, and a query processor for an object oriented (OO) query language, AMOSQL [5] AMOSQL is similar to the ....

....is a mediator server servicing inter mediator requests from other mediators and defining mediating OO views integrating data from other mediator servers. E) is a mediator server that translates data from a wrapped relational database. It has knowledge of how to translate AMOSQL queries to SQL [3] and interfaces to call SQL through ODBC [4] It can use the facilities of AMOSQL for semantic reconciliation of data from its data source and its local database into views presented to other systems. F) is a stand alone database server accessed from mediator (D) by TCP IP. It is also a name ....

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Fahl G, Risch T. Query processing over object views of relational data. The VLDB Journal 1997; 6(4):261--281.

....to the data itself by using object ids. There are basically two solutions to this mismatch. First, an object id generated at object creation time could be stored in one column for each database table [Ambler 98] Second, a mapping algorithm between primary keys and the object ids could be used [Fahl Risch 97] The first approach is the easiest one to implement but requires database changes, which may not be possible to do when integrating legacy databases. The second approach is harder to implement. In this approach the mapping, for example, becomes invalid if primary keys are reused. 3.1.4 ....

G. Fahl, T. Risch. Query processing over object views of relational data. The VLDB Journal 6:261-281. SpringerVerlag, Germany, 1997.

....the relational schema simply does not carry the necessary information. Hence, the mapping rules must be specified by a human operator, as done in our approach. The translation of object oriented queries into a query against a semantically equivalent relational schema is covered in depth in [5] and [13] The approach of [5] is similar to ours in that they also assume that each (object oriented) class is represented by exactly one (relational) table. However, our query language is only a subset of theirs, as we do not treat path expressions. 13] considers extensional relationships in ....

....does not carry the necessary information. Hence, the mapping rules must be specified by a human operator, as done in our approach. The translation of object oriented queries into a query against a semantically equivalent relational schema is covered in depth in [5] and [13] The approach of [5] is similar to ours in that they also assume that each (object oriented) class is represented by exactly one (relational) table. However, our query language is only a subset of theirs, as we do not treat path expressions. 13] considers extensional relationships in inheritance hierarchies by ....

Fahl G., and Risch T.: Query Processing over Object Views of Relational Data. The VLDB Journal 6(4). Springer-Verlag (1997) 261-281

....[Fah93] AMOS, is a research platform for experimenting with specialized database systems. It is a fast main memory object relational database with a data dictionary, a query language, transactions, database procedures [Flo96] multi database queries [Wer96] access to relational databases [Fah94][Fah96], and active rules [Sk 96] The query and modeling language of AMOS, AMOSQL, is a derivative of OSQL [Fis89] and is based on the DAPLEX functional data model [Shi81] The system supports high level object oriented abstractions and declarative queries for extracting and manipulating data. A foreign ....

Fahl, G, Risch, T., Query Processing over Object Views of Relational Data, Technical report LiTH-IDA-R-95-11, Linköping University, Sweden, (Revised version accepted at VLDB J.)

.... SQL3[Mel95] et OQL[Cat94] Comme dans OSQL, les requ tes AMOSQL sont compil es des plans d ex cution dans un langage logique OO appell Object Log[LR92] AMOSQL tend OSQL principalement avec des r gles actives et un syst me plus riche en types et en fonctionalit s de base de donn es multiples [FaR97]. Dans sa premiere version le langage de r gles dans AMOS ne supporte que des r gles de type CA (Condition Action) o les v nements entra n s sont calcul s partir des Conditions par le compilateur de r gles. Ces r gles sont d clench es implicitement quand des donn es sont modifi es et les ....

....and OSQL[Lyn91] The Iris data model has three basic modelling constructs; objects, types and functions and everything in the model is an object including types and functions. The AMOS data model extends that of Iris by introducing rules, a richer type system and multidatabase facilities [Fah94, FaR97]. Further more AMOSQL is influenced by the standardisation efforts such as SQL3[Mel95] and OQL[Cat94] Rules are also objects and of type rule . The relationship between objects, types, functions and rules in AMOS can be seen in figure 2.1. Objects are used to model entities in the domain of ....

Fahl G., Risch T.: Query processing over object views of relational data, to appear in VLDB journal 1997.

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Gustav Fahl and Tore Risch. Query Processing Over Object Views of Relational Data. VLDB Journal, 6(4):261--281, 1997.

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G. Fahl and T. Risch. Query processing over object views of relational data. VLDB Journal, 6(4):261--281, 1997.

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G. Fahl, T. Risch. Query Processing over Object Views of Relational Data. The VLDB Journal, 6(4), pages 261-281, 1997.

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G. Fahl and T. Risch. Query processing over object views of relational data. VLDB Journal, 6(4):261--281, 1997.

....to rules below. Figure 1: Distributed Amos II mediators XML files OODB ODBC Wrapper Mediator Wrapper Wrapper Mediator Wrapper Application Mediator Application Step files 4 In addition to basic OO data management facilities Amos II also provides OO data mediation facilities [Fahl(1997)] Josifovski(1999A) Josifovski(1999B) By utilizing these facilities we can query combinations of XML data, relational databases and other kinds of data sources, as illustrated in Figure 1. It shows an example of distributed mediation with Amos II where two applications access data from four ....

....accessed XML documents. When conflicting schema definitions are discovered the system automatically adapts the dynamically generated schema and database to be general enough to represent all XML data. The discovery of OO schema structures combined 10 with other OO mediation facilities in Amos II [Fahl(1997)] Josifovski(1999A) Josifovski(1999B) allow the specification OO queries and views over data from XML documents combined with data from other data sources. The incremental nature of the translation rules allow them to be applied in a streamed fashion, which is important for large data files ....

Fahl, G. and Risch, T. (1997). Query Processing over Object Views of Relational Data, VLDB Journal, Vol. 6 No. 4, 261-281.

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Fahl G, Risch T: Query processing over object views of relational data. The vldb Journal, Vol. 6 No. 4 November, 1997, pp 261-281.

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Gustav Fahl, Tore Risch, "Query Processing Over Object Views of Relational Data", VLDB Journal 6(4) 1997, pp. 261-281.

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