Clustering IndexPrimary IndexSpringer USdoi:10.1007/978-0-387-39940-9_2216
1 alter table foo add clustering index (a,b); Syntactic simplification The intent of a clustering index definition is easier to understand because it only includes columns necessary to achieve the desired sort order. Columns needed to satisfy the select clause can be left out. As users add mor...
centroids=randCent(dataSet,k)clusterChanged=TruewhileclusterChanged:clusterChanged=Falseforiinrange(m):#foreach data point assign it to the closest centroid minDist=inf;minIndex=-1forjinrange(k):distJI=distEclud(centroids[j,:],dataSet[i,:])ifdistJI<minDist:minDist=distJI;minIndex=jifclusterA...
亦称聚类“有效性指标”(validity index),与监督学习中的性能度量作用相似,对聚类结果我们需要通过某种性能度量来评估其好坏;另一方面若明确了最终将要使用的性能度量,则可直接将其作为聚类过程的优化目标,从而更好地得到符合要求的聚类结果。聚类性能度量大致有两类,一类是将聚类结果与某个“参考模型”进行比较,称为“...
Range Clustering作为一种新的数据切分方式,提供了一个全局有序的数据分布,一是可以避免Hash Clustering可能造成的数据倾斜问题;二是在数据有序分布的前提下,创建两级索引(Index),支持对Clustering Key的区域查询以及多键的组合查询等场景。本文为您介绍如何在MaxCompute中使用Range Clustering。 背景信息 哈希聚簇(Hash ...
CCIndex: A Complemental Clustering Index on Distributed Ordered Tables for Multi-dimensional Range Queries Yongqiang Zou, Jia Liu, Shicai Wang, Li Zha, and Zhiwei Xu Institute of Computing Technology, Chinese Academy of Sciences Beijing, 100190, China {zouyongqiang,liujia09,wangshicai}@software.ict...
Caches, local caches which is basically the Lucene Index tmp Monitoring data dbconfig.xml cluster.properties Shared Home Data including attachments and avatars Caches, shared Export Import PluginsThe method JiraHome.getHome() returns the shared home. A new method getLocalHome() returns the local ...
#function that creates a dataframe with a column for cluster number def pd_centers(cols_of_interest, centers): colNames = list(cols_of_interest) colNames.append('prediction') # Zip with a column called 'prediction' (index) Z = [np.append(A, index) for index, A in enumerate(centers)]...
同樣的資料、同樣的查詢,使用Hash Clustering表來做,可以直接定位到單個Bucket,並利用Index唯讀取包含查詢資料的Page,只用4個Mapper,讀取10000條記錄,總共耗時只需要6秒。 Aggregation最佳化 對於以下查詢: SELECT department, SUM(salary) FROM employee GROUP BY (department); 通常情況下會對department列資料進行...
The galaxy size and Sérsic index data can be downloaded at http://sdss.physics.nyu.edu/vagc/. The galaxy group catalogue is publicly available at https://gax.sjtu.edu.cn/data/Group.html. The ALFALFA H i sample can be downloaded at https://egg.astro.cornell.edu/alfalfa/data/. The...