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基于邻接表存储与哈希表的频繁项集挖掘算法
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作者 吴昊 刘钊 顾进广 《计算机应用与软件》 北大核心 2023年第7期266-273,共8页
针对Apriori算法从数据中挖掘频繁项集的计算时间效率较低和空间内存占用较高的问题提出一种ATSAHT-Apriori(Adjacency Table Storage and Hash Table-Apriori)算法。该算法利用哈希表来存储数据,极大地提高了项集支持度频数的计算效率... 针对Apriori算法从数据中挖掘频繁项集的计算时间效率较低和空间内存占用较高的问题提出一种ATSAHT-Apriori(Adjacency Table Storage and Hash Table-Apriori)算法。该算法利用哈希表来存储数据,极大地提高了项集支持度频数的计算效率,结合图存储的思想利用邻接表来存储候选项集,极大地优化了内存空间占用,同时将候选项集构建大根堆,通过堆排序的思想与动态剪枝算法思想优化了频繁项集的计算速度和候选项集存储的内存空间,有效地优化了传统Apriori算法的计算时间效率和内存空间占用方面的不足。一系列对比实验表明,ATSAHT-Apriori算法在时间效率和空间效率都有一定的提高。 展开更多
关键词 时间复杂度 空间复杂度 动态剪枝 哈希表存储 邻接存储
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井下人员定位系统读卡器存储算法分析与测试 被引量:2
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作者 张峰 徐钊 张凯婷 《工矿自动化》 北大核心 2012年第8期79-82,共4页
从查找时间与存储容量2个方面分析了适用于井下人员定位系统读卡器的3种存储算法,即链式存储算法、哈希表存储算法和哈希二叉树存储算法,给出了该3种不同存储算法的使用效率与应用场合。测试结果表明,链式存储算法查找时间呈线性增长,... 从查找时间与存储容量2个方面分析了适用于井下人员定位系统读卡器的3种存储算法,即链式存储算法、哈希表存储算法和哈希二叉树存储算法,给出了该3种不同存储算法的使用效率与应用场合。测试结果表明,链式存储算法查找时间呈线性增长,哈希表存储算法明显优越于链式存储算法,如果测试数据增多,其优越性会更明显;当数据量较大时,哈希搜索二叉树存储算法又明显优于哈希表存储算法,当人数达到行业所要求的8 000人以上时,选择哈希搜索二叉树存储算法更为合理。 展开更多
关键词 人员定位 读卡器 链式存储算法 哈希表存储算法 哈希搜索二叉树存储算法
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A reliable power management scheme for consistent hashing based distributed key value storage systems 被引量:1
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作者 Nan-nan ZHAO Ji-guang WAN +1 位作者 Jun WANG Chang-sheng XIE 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2016年第10期994-1007,共14页
Distributed key value storage systems are among the most important types of distributed storage systems currently deployed in data centers. Nowadays, enterprise data centers are facing growing pressure in reducing the... Distributed key value storage systems are among the most important types of distributed storage systems currently deployed in data centers. Nowadays, enterprise data centers are facing growing pressure in reducing their power consumption. In this paper, we propose GreenCHT, a reliable power management scheme for consistent hashing based distributed key value storage systems. It consists of a multi-tier replication scheme, a reliable distributed log store, and a predictive power mode scheduler (PMS). Instead of randomly placing replicas of each object on a number of nodes in the consistent hash ring, we arrange the replicas of objects on nonoverlapping tiers of nodes in the ring. This allows the system to fall in various power modes by powering down subsets of servers while not violating data availability. The predictive PMS predicts workloads and adapts to load fluctuation. It cooperates with the multi-tier replication strategy to provide power proportionality for the system. To ensure that the reliability of the system is maintained when replicas are powered down, we distribute the writes to standby replicas to active servers, which ensures failure tolerance of the system. GreenCHT is implemented based on Sheepdog, a distributed key value storage system that uses consistent hashing as an underlying distributed hash table. By replaying 12 typical real workload traces collected from Microsoft, the evaluation results show that GreenCHT can provide significant power savings while maintaining a desired performance. We observe that GreenCHT can reduce power consumption by up to 35%-61%. 展开更多
关键词 Consistent hash table (CHT) REPLICATION Power management Key value storage system Reliability
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