Partial Answers for Unavailable Data Sources

Philippe Bonnet Anthony Tomasic 1
1 RODIN - Database Systems
Inria Paris-Rocquencourt
Abstract : Many heterogeneous database system products and prototypes exist today; they will soon be deployed in a wide variety of environments. All existing systems suffer from an {\em Achilles' heel}: if some sources are unavailable when accessed, these systems either silently ignore them or generate an error, i.e. they {\em ungraciously fail}. This behavior is improper in environments where there is a non-negligible probability that data sources cannot be accessed (e.g., Internet). In this paper, we propose a novel approach to this issue where, in presence of unavailable data sources, the answer to a query is a {\em partial answer}. A partial answer is itself a query that results from theo partial evaluation of the original query; it is composed of the data that have been obtained and processed during the evaluation and of a representation of the unfinished work to be done. Partial answers can be resubmitted to the system in order to obtain the final answer to the original query, or another partial answer. Additionally, the application program can extract information from a partial answer through the use of a secondary query. This secondary query is called a {\em parachute query}. In this paper we give a taxonomy of partial answers and parachute queries. We present algorithms for the evaluation of queries in presence of unavailable data sources, and we describe an implementation.
Type de document :
Rapport
[Research Report] RR-3127, INRIA. 1997
Liste complète des métadonnées

https://hal.inria.fr/inria-00073562
Contributeur : Rapport de Recherche Inria <>
Soumis le : mercredi 24 mai 2006 - 13:11:46
Dernière modification le : vendredi 25 mai 2018 - 12:02:05
Document(s) archivé(s) le : dimanche 4 avril 2010 - 21:35:06

Fichiers

Identifiants

  • HAL Id : inria-00073562, version 1

Collections

Citation

Philippe Bonnet, Anthony Tomasic. Partial Answers for Unavailable Data Sources. [Research Report] RR-3127, INRIA. 1997. 〈inria-00073562〉

Partager

Métriques

Consultations de la notice

102

Téléchargements de fichiers

147