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Complex spatial query processing / Nikos Mamoulis in Geoinformatica, vol 8 n° 4 (December 2004)  

Public [article]  inGeoinformatica > vol 8 n° 4 (December 2004) . - pp 311 - 346 Titre : Complex spatial query processing Type de document : Article/Communication Auteurs : Nikos Mamoulis, Auteur ; Dimitris Papadias, Auteur ; D. Arkoumanis, Auteur Année de publication : 2004 Article en page(s) : pp 311 - 346 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] base de données localisées [Termes IGN] jointure spatiale [Termes IGN] optimisation (mathématiques) [Termes IGN] requête spatiale Résumé : (Auteur) The user of a Geographical Information System is not limited to conventional spatial selections and joins, but may also pose more complicated and descriptive queries. In this paper, we focus on the efficient processing and optimization of complex spatial queries that involve combinations of spatial selections and joins. Our contribution is manifold; we first provide formulae that accurately estimate the selectivity of such queries. These formulae, paired with cost models for selections and joins can be used to combine spatial operators in an optimal way. Second, we propose algorithms that process spatial joins and selections simultaneously and are typically more efficient than combinations of simple operators. Finally we study the problem of optimizing complex spatial queries using these operators, by providing (i) cost models, and (ii) rules that reduce the optimization space significantly. The accuracy of the selectivity models and the efficiency of the proposed algorithms are evaluated through experimentation. Numéro de notice : A2004-391 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1023/B:GEIN.0000040830.73424.f0 En ligne : https://doi.org/10.1023/B:GEIN.0000040830.73424.f0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26918 [article]

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057-04041	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Search algorithms for multiway spatial joins / Dimitris Papadias in International journal of geographical information science IJGIS, vol 16 n° 7 (october 2002)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 16 n° 7 (october 2002) . - pp 613 - 639 Titre : Search algorithms for multiway spatial joins Type de document : Article/Communication Auteurs : Dimitris Papadias, Auteur ; D. Arkoumanis, Auteur Année de publication : 2002 Article en page(s) : pp 613 - 639 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] arbre-R [Termes IGN] jointure spatiale [Termes IGN] recherche heuristique [Termes IGN] requête spatiale [Termes IGN] temps réel Résumé : (Auteur) This paper deals with multiway spatial joins when (i) there is limited time for query processing and the goal is to retrieve the best possible solutions within this limit (ii) there is unlimited time and the goal is to retrieve a single exact solution, if such a solution exists, or the best approximate one otherwise. The first case is motivated by the high cost of join processing in real-time systems involving large amounts of multimedia data, while the second one is motivated by applications that require 'negative' examples. We propose several search algorithms for query processing under theses conditions. For the limited-time case we develop some non-deterministic search heuristics that can quickly retrieve good solutions. However, these heuristics are not guaranteed to find the best solutions, even without a time limit. Therefore, for the unfirnited-time case we describe systematic search algorithms tailored specifically for the efficient retrieval of a single solution. Both types of algorithms are integrated with R-trees in order to prune the search space. Our proposal is evaluated with extensive experimental comparison. Numéro de notice : A2002-209 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1080/13658810210138733 En ligne : https://doi.org/10.1080/13658810210138733 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22124 [article]

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079-02071	RAB	Revue	Centre de documentation	En réserve L003	Disponible