The original paper is in English. Non-English content has been machine-translated and may contain typographical errors or mistranslations. ex. Some numerals are expressed as "XNUMX".
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The original paper is in English. Non-English content has been machine-translated and may contain typographical errors or mistranslations. Copyrights notice
O objetivo deste artigo é apresentar algoritmos para criação de um plano de consulta otimizado para recuperar o máximo de informações de múltiplas relações, utilizando outerjoins. Focamos especialmente em consultas conjuntivas na presença de predicados e funções estrangeiras. Mostramos primeiro com exemplos que a recuperação do máximo de informações através da integração de múltiplas relações requer operadores de junção externa. A junção externa é essencial para evitar a perda de informações que seria causada pela junção interna. Mostramos também que predicados e funções estrangeiras são úteis para mediar a discrepância entre as relações e para criar visões arbitrárias. Outerjoins e funções estrangeiras, juntamente com predicados, dificultam a criação de planos de processamento de consultas, pois impõem restrições à ordem de processamento das consultas. O restante deste artigo descreve algoritmos para criar tais planos de processamento de consultas para consultas conjuntivas expressas em Datalog estendido. Primeiro, mostramos algoritmos simples para criar planos de consulta com outerjoins, mas sem predicados e funções estrangeiras. Usamos a representação hipergráfica das relações para explicar um algoritmo otimizado. Em seguida, mostramos um algoritmo mais complexo que funciona para planos de consulta com predicados e funções estrangeiras. Em nosso algoritmo, criamos um gráfico de expressão inicial cujos nós representam unidades de processamento de consulta, incluindo operadores de junção externa, predicado e função estrangeira. Em seguida, convertemos o gráfico de expressão inicial em uma árvore de expressão executável e otimizada. Este algoritmo é implementado e implantado em um sistema de mediação que integra fontes de informação heterogêneas.
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Koichi MUNAKATA, "Integration of Maximum Information Using Outerjoins, Predicates and Foreign Functions" in IEICE TRANSACTIONS on Information,
vol. E82-D, no. 1, pp. 64-75, January 1999, doi: .
Abstract: The goal of this paper is to present algorithms for creating an optimized query plan for retrieving maximum information from multiple relations, using outerjoins. Especially we focus on conjunctive queries in the presence of predicates and foreign functions. We show first with examples that retrieving maximum information by integrating multiple relations requires outerjoin operators. The outerjoin is essential to prevent information loss that would be caused by the inner join. We also show that predicates and foreign functions are useful to mediate the discrepancy among the relations and to create arbitrary views. Outerjoins and foreign functions, together with predicates, make it difficult to create query processing plans since they impose restrictions on the order of query processing. The rest of this paper describes algorithms for creating such query processing plans for conjunctive queries expressed in extended Datalog. First, we show simple algorithms for creating query plans with outerjoins, but without predicates and foreign functions. We use the hypergraph representation of the relations to explain an optimized algorithm. Then, we show a more complex algorithm that works for query plans with predicates and foreign functions. In our algorithm, we create an initial expression graph whose nodes represent query processing units, including outerjoin, predicate and foreign function operators. Then, we convert the initial expression graph into an executable, optimized expression tree. This algorithm is implemented and deployed in a mediation system that integrates heterogeneous information sources.
URL: https://global.ieice.org/en_transactions/information/10.1587/e82-d_1_64/_p
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@ARTICLE{e82-d_1_64,
author={Koichi MUNAKATA, },
journal={IEICE TRANSACTIONS on Information},
title={Integration of Maximum Information Using Outerjoins, Predicates and Foreign Functions},
year={1999},
volume={E82-D},
number={1},
pages={64-75},
abstract={The goal of this paper is to present algorithms for creating an optimized query plan for retrieving maximum information from multiple relations, using outerjoins. Especially we focus on conjunctive queries in the presence of predicates and foreign functions. We show first with examples that retrieving maximum information by integrating multiple relations requires outerjoin operators. The outerjoin is essential to prevent information loss that would be caused by the inner join. We also show that predicates and foreign functions are useful to mediate the discrepancy among the relations and to create arbitrary views. Outerjoins and foreign functions, together with predicates, make it difficult to create query processing plans since they impose restrictions on the order of query processing. The rest of this paper describes algorithms for creating such query processing plans for conjunctive queries expressed in extended Datalog. First, we show simple algorithms for creating query plans with outerjoins, but without predicates and foreign functions. We use the hypergraph representation of the relations to explain an optimized algorithm. Then, we show a more complex algorithm that works for query plans with predicates and foreign functions. In our algorithm, we create an initial expression graph whose nodes represent query processing units, including outerjoin, predicate and foreign function operators. Then, we convert the initial expression graph into an executable, optimized expression tree. This algorithm is implemented and deployed in a mediation system that integrates heterogeneous information sources.},
keywords={},
doi={},
ISSN={},
month={January},}
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TY - JOUR
TI - Integration of Maximum Information Using Outerjoins, Predicates and Foreign Functions
T2 - IEICE TRANSACTIONS on Information
SP - 64
EP - 75
AU - Koichi MUNAKATA
PY - 1999
DO -
JO - IEICE TRANSACTIONS on Information
SN -
VL - E82-D
IS - 1
JA - IEICE TRANSACTIONS on Information
Y1 - January 1999
AB - The goal of this paper is to present algorithms for creating an optimized query plan for retrieving maximum information from multiple relations, using outerjoins. Especially we focus on conjunctive queries in the presence of predicates and foreign functions. We show first with examples that retrieving maximum information by integrating multiple relations requires outerjoin operators. The outerjoin is essential to prevent information loss that would be caused by the inner join. We also show that predicates and foreign functions are useful to mediate the discrepancy among the relations and to create arbitrary views. Outerjoins and foreign functions, together with predicates, make it difficult to create query processing plans since they impose restrictions on the order of query processing. The rest of this paper describes algorithms for creating such query processing plans for conjunctive queries expressed in extended Datalog. First, we show simple algorithms for creating query plans with outerjoins, but without predicates and foreign functions. We use the hypergraph representation of the relations to explain an optimized algorithm. Then, we show a more complex algorithm that works for query plans with predicates and foreign functions. In our algorithm, we create an initial expression graph whose nodes represent query processing units, including outerjoin, predicate and foreign function operators. Then, we convert the initial expression graph into an executable, optimized expression tree. This algorithm is implemented and deployed in a mediation system that integrates heterogeneous information sources.
ER -