hadoop2.7 +hive 1.2 select count(*) 没出结果

2015-09-28 02:30:27 1.1k 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

关于HIVE的SELECT count(*) 优化刚刚下载了一份HIVE的最新源码。印象最深的是HIVE将表的大小作为了元数据保存在了关系数据库中。譬如在老版本中执行如下的语句： from base insert overwrite table user select * ; 你会发现日志的末尾会有 “999 ROWD LOADED INTO TABLE USER” 的字样代表有999条目记录保存在了user表阅读详情

hadoop 日志：
Hadoop job information for Stage-1: number of mappers: 0; number of reducers: 0
2015-09-28 14:29:09,714 Stage-1 map = 0%, reduce = 0%
Ended Job = job_1443420059144_0002 with errors
Error during job, obtaining debugging information...
FAILED: Operation cancelled
MapReduce Jobs Launched:
Stage-Stage-1: HDFS Read: 0 HDFS Write: 0 FAIL
Total MapReduce CPU Time Spent: 0 msec
Query ID = root_20150928142912_002ed404-1b70-418a-9046-9290f0aacf2e
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_1443420059144_0003, Tracking URL = http://hadoopmaster:8088/proxy/application_1443420059144_0003/
Kill Command = /usr/local/hadoop-2.7.1/bin/hadoop job -kill job_1443420059144_0003

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