数据块采样抽取百分之一的数据出来代码,Hive代码库,德仔网

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【Hive】数据块采样抽取百分之一的数据出来

作者: / 发布于2016/11/28/ 187

hive>  
    > select count(*) from salaries_external tablesample(0.1 percent);  
Total jobs = 1  
Launching Job 1 out of 1  
Number of reduce tasks determined at compile time: 1  
In order to change the average load for a reducer (in bytes):  
  set hive.exec.reducers.bytes.per.reducer=<number>  
In order to limit the maximum number of reducers:  
  set hive.exec.reducers.max=<number>  
In order to set a constant number of reducers:  
  set mapreduce.job.reduces=<number>  
Starting Job = job_1475147088438_0006, Tracking URL = http://hadoopwy1:8088/proxy/application_1475147088438_0006/  
Kill Command = /usr/local/hadoop2/bin/hadoop job  -kill job_1475147088438_0006  
Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 1  
2016-09-29 05:13:14,531 Stage-1 map = 0%,  reduce = 0%  
2016-09-29 05:13:35,510 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 1.62 sec  
2016-09-29 05:13:47,117 Stage-1 map = 100%,  reduce = 100%, Cumulative CPU 3.0 sec  
MapReduce Total cumulative CPU time: 3 seconds 0 msec  
Ended Job = job_1475147088438_0006  
MapReduce Jobs Launched:  
Job 0: Map: 1  Reduce: 1   Cumulative CPU: 3.0 sec   HDFS Read: 677182 HDFS Write: 6 SUCCESS  
Total MapReduce CPU Time Spent: 3 seconds 0 msec  
OK  
23142  
Time taken: 45.085 seconds, Fetched: 1 row(s)

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