UNETMAN

如何设置Hadoop  Map/Reduce任务的内存限制？ Parameter Type Meaning mapred.cluster.map.memory.mb set by admin, cluster-wide Cluster definition of memory per map slot. The maximum amount of memory, in MB, ea

第一部分：关系运算 Hive支持的关系运算符 •常见的关系运算符 •等值比较: = •不等值比较: •小于比较: •小于等于比较: •大于比较: > •大于等于比较: >= •空值判断: IS NULL •非空判断: IS NOT NULL •LIKE比较: LIKE •JAVA的LIKE操作: RLIKE •REGEXP操作: REGE

1.将本地文件拷贝到 hdfs 文件系统中  bin/hadoop fs -copyFromLocal /server/bin/nutch/urls/url.txt   urls  2.将hdfs中的文件拷贝到本地路径  bin/hadoop fs -copyToLocal  urls(hdfs文件)  /opt/index (本地路径)  3.查看hdfs文件系统内文件列

1.创建表的语句： Create [EXTERNAL] TABLE [IF NOT EXISTS] table_name [(col_name data_type [COMMENT col_comment], ...)] [COMMENT table_comment] [PARTITIONED BY (col_name data_type [COMMENT col_comment],