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Rahmani Amir Masoud Azhir Elham Naserbakht Morteza Mohammadi Mokhtar Aldalwie Adil Hussein Mohammed Majeed Mohammed Kamal Taher Karim Sarkhel H. Hosseinzadeh Mehdi 《Multimedia Tools and Applications》2022,81(20):28799-28800
Multimedia Tools and Applications - 相似文献
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Elham Azhir Nima Jafari Navimipour Mehdi Hosseinzadeh Arash Sharifi Aso Darwesh 《International Journal of Communication Systems》2019,32(8)
The goal of a query optimizer is to provide an optimal Query Execution Plan (QEP) by comparing alternative query plans. In a distributed database system over cloud environment, the relations required by a query plan may be stored at multiple sites. This leads to an exponential increase in the number of possible equivalent plan alternatives to find an optimal QEP. Although it is not computationally reasonable to explore exhaustively all possible plans in such large search space. Although query optimization mechanisms are important in the cloud environments, to the best of our knowledge, there exists no complete and systematic review on investigating these issues. Therefore, in this paper, four categories to study these mechanisms are considered which are search‐based, machine learning‐based, schema‐based, and security‐based mechanisms. Also, this paper represents the advantages and disadvantages of the selected query optimization techniques and investigates the metrics of their techniques. Finally, the important challenges of these techniques are reviewed to develop more efficient query optimization techniques in the future. 相似文献
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Rahmani Amir Masoud Azhir Elham Naserbakht Morteza Mohammadi Mokhtar Aldalwie Adil Hussein Mohammed Majeed Mohammed Kamal Taher Karim Sarkhel H. Hosseinzadeh Mehdi 《Multimedia Tools and Applications》2022,81(20):28779-28798
Multimedia Tools and Applications - Since early 2020, Coronavirus Disease 2019 (COVID-19) has spread widely around the world. COVID-19 infects the lungs, leading to breathing difficulties. Early... 相似文献
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