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Performance evaluations on inner vs. outer decomposition first parallel join algorithms for two nested loop joins
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作者 Seo-Young NOH Heejun YOON +2 位作者 Il-Yeon YEO Yoon-su JEONG Hyungwoo PARK 《Journal of Central South University》 SCIE EI CAS 2014年第10期3873-3882,共10页
Two popular traditional join algorithms and their parallel versions are introduced. When designing join algorithms in serial computing environment, decomposing inner relation is considered as the right direction to sa... Two popular traditional join algorithms and their parallel versions are introduced. When designing join algorithms in serial computing environment, decomposing inner relation is considered as the right direction to save disk I/Os. However, two different decomposition algorithms are compared, such as inner vs. outer decomposition first algorithms for tuple-based and block-based nested loop joins, showing that the proposed approach is 20% better than general approach. Also lemmas are proved, when we have to use the outer decomposition first parallel join algorithms. 展开更多
关键词 parallel join performance inner decomposition outer decomposition
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A study on coupling technique and implementation of the wave-circulation coupled model 被引量:1
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作者 张志远 Liu Li +5 位作者 Zhou Yufeng Zhang Cheng Li Ruizhe Chen Yushu Song Guojie Yang Guangwen 《High Technology Letters》 EI CAS 2014年第1期82-87,共6页
The coupler is fundamental for a coupled model to realize complex interactions among component models.This paper focuses on the coupling process of Wave-Circulation(W-C) coupled model which consists of MASNUM(key labo... The coupler is fundamental for a coupled model to realize complex interactions among component models.This paper focuses on the coupling process of Wave-Circulation(W-C) coupled model which consists of MASNUM(key laboratory of marine science and numerical modeling wave model)and POM(Princeton Ocean Model).The current coupling module of this coupled model is based on the inefficient I/O file,which has already become a performance bottleneck especially when the coupled model utilizes a large number of processes.To improve the performance of the W-C model,a flexible coupling module based on the model coupling toolkit(MCT) is designed and implemented to replace the current I/O file coupling module in the coupled model.Empirical studies that we have carried out demonstrate that our online coupling module can dramatically improve the parallel performance of the coupled model.The online coupling module outperforms the I/O file coupling module.When processes increase to 96,the whole process of EXP-C takes only 695.8 seconds,which is only 58.8%of the execution time of EXP-F.Based on our experiments under 2D Parallel Decomposition(2DPD),we suggest setting parallel decomposition strategies automatically to component models in order to achieve high parallel efficiency. 展开更多
关键词 coupling technique model coupling toolkit (MCT) W-C coupled online cou-pling module 2D parallel Decomposition (2DPD) parallel performance
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