Think big, start small: a good initiative to design green query optimizers

2019 ◽  
Vol 23 (3) ◽  
pp. 2323-2345
Author(s):  
Simon Pierre Dembele ◽  
Ladjel Bellatreche ◽  
Carlos Ordonez ◽  
Amine Roukh
Keyword(s):  
2018 ◽  
Vol 8 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Manik Sharma ◽  
Gurvinder Singh ◽  
Rajinder Singh

2021 ◽  
Author(s):  
Srikanth Kandula ◽  
Laurel Orr ◽  
Surajit Chaudhuri
Keyword(s):  

Author(s):  
Andreas M. Weiner ◽  
Theo Härder

Since the very beginning of query processing in database systems, cost-based query optimization has been the essential strategy for effectively answering complex queries on large documents. XML documents can be efficiently stored and processed using native XML database management systems. Even though such systems can choose from a huge repertoire of join operators (e. g., Structural Joins and Holistic Twig Joins) and various index access operators to efficiently evaluate queries on XML documents, the development of full-fledged XML query optimizers is still in its infancy. Especially the evaluation of complex XQuery expressions using these operators is not well understood and needs further research. The extensible, rule-based, and cost-based XML query optimization framework proposed in this chapter, serves as a testbed for exploring how and whether well-known concepts from relational query optimization (e. g., join reordering) can be reused and which new techniques can make a significant contribution to speed-up query execution. Using the best practices and an appropriate cost model that will be developed using this framework, it can be turned into a robust cost-based XML query optimizer in the future.


2009 ◽  
Vol 37 (4) ◽  
pp. 28-34 ◽  
Author(s):  
Alpa Jain ◽  
Panagiotis Ipeirotis ◽  
Luis Gravano

2021 ◽  
Vol Volume 34 - 2020 - Special... ◽  
Author(s):  
Simon Pierre Dembele ◽  
Ladjel Bellatreche ◽  
Carlos Ordonez ◽  
Nabil Gmati ◽  
Mathieu Roche ◽  
...  

Soumission à Episciences International audience Computers and electronic machines in businesses consume a significant amount of electricity, releasing carbon dioxide (CO2), which contributes to greenhouse gas emissions. Energy efficiency is a pressing concern in IT systems, ranging from mobile devices to large servers in data centers, in order to be more environmentally responsible. In order to meet the growing demands in the awareness of excessive energy consumption, many initiatives have been launched on energy efficiency for big data processing covering electronic components, software and applications. Query optimizers are one of the most power consuming components of a DBMS. They can be modified to take into account the energetical cost of query plans by using energy-based cost models with the aim of reducing the power consumption of computer systems. In this paper, we study, describe and evaluate the design of three energy cost models whose values of energy sensitive parameters are determined using the Nonlinear Regression and the Random Forests techniques. To this end, we study in depth the operating principle of the selected DBMS and present an analysis comparing the performance time and energy consumption of typical queries in the TPC benchmark. We perform extensive experiments on a physical testbed based on PostreSQL, MontetDB and Hyrise systems using workloads generatedusing our chosen benchmark to validate our proposal. Les ordinateurs et les machines électroniques des entreprises consomment une quantité importante d’électricité, libérant ainsi du dioxyde de carbone (CO2), qui contribue aux émissions de gaz à effet de serre. L’efficacité énergétique est une préoccupation urgente dans les systèmesinformatiques, partant des équipements mobiles aux grands serveurs dans les centres de données, afin d’être plus respectueux envers l’environnement. Afin de répondre aux exigences croissantes en matière de sensibilisation à l’utilisation excessive de l’énergie, de nombreuses initiatives ont été lancées sur l’efficacité énergétique pour le traitement des données massives couvrant les composantsélectroniques, les logiciels et les applications. Les optimiseurs de requêtes sont l’un des composants les plus énergivores d’un SGBD. Ils peuvent être modifiés pour prendre en compte le coût énergétique des plans des requêtes à l’aide des modèles de coût énergétiques intégrés dans l’optimiseur dans le but de réduire la consommation électrique des systèmes informatiques. Dans cet article, nousétudions, décrivons et évaluons la conception de trois modèles de coût énergétique dont les valeurs des paramètres sensibles à l’énergie sont définis en utilisant la technique de la Régression non linéaire et la technique des forêts aléatoires. Pour ce fait, nous menons une étude approfondie du principe de fonctionnement des SGBD choisis et présentons une analyse des performances en termes de temps et énergie sur des requêtes typiques du benchmarks TPC-H. Nous effectuons des expériences approfondies basées sur les systèmes PostgreSQL, MonetDB et Hyrise en utilisant un jeu de données généré à partir du benchmarks TPC-H afin de valider nos propositions.


Author(s):  
Victor Muntés-Mulero ◽  
Néstor Lafón-Gracia ◽  
Josep Aguilar-Saborit ◽  
Josep-L. Larriba-Pey
Keyword(s):  

Author(s):  
Michael Sokolov

Query optimizers often mystify database users: sometimes queries run quickly and sometimes they don’t. An intuitive grasp of what will work well in an optimizer is often gained only after trial, error, inductive logic (i.e. educated guessing), and sometimes propitiatory sacrifice. This paper tries to lift the veil by describing work on Lux, a new indexed XQuery search engine built using Saxon and Lucene, which is freely available under an open-source license. Lux optimizes queries by rewriting them as equivalent (but usually faster) indexed queries, so its results are easier for a user to understand than the abstract query plans produced by some optimizers. Lucene-based QName and path indexes prove useful in speeding up XQuery execution by Saxon.


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