Hi there, I loaded data from the movielens database into hive, into a u_data table. I wish I could count the total number of rows in that table. Although mapreduce task starts, it ends with a Null Pointer Exception.
I must admit I don't know what to do next, how to investigate this issue. The standard output is as follows : hive> describe u_data; OK userid int movieid int rating int unixtime string Time taken: 3.421 seconds hive> select count(1) from u_data where userid=1; Total MapReduce 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 mapred.reduce.tasks=<number> Starting Job = job_201212161709_0002, Tracking URL = http://localhost.localdomain:50030/jobdetails.jsp?jobid=job_201212161709_0002 Kill Command = /usr/lib/hadoop/bin/hadoop job -Dmapred.job.tracker=localhost.localdomain:8021 -kill job_201212161709_0002 Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 1 2012-12-16 18:07:55,502 Stage-1 map = 0%, reduce = 0% 2012-12-16 18:08:15,627 Stage-1 map = 100%, reduce = 100% Ended Job = job_201212161709_0002 with errors Error during job, obtaining debugging information... Examining task ID: task_201212161709_0002_m_000002 (and more) from job job_201212161709_0002 Exception in thread "Thread-23" java.lang.NullPointerException at org.apache.hadoop.hive.shims.Hadoop23Shims.getTaskAttemptLogUrl(Hadoop23Shims.java:44) at org.apache.hadoop.hive.ql.exec.JobDebugger$TaskInfoGrabber.getTaskInfos(JobDebugger.java:186) at org.apache.hadoop.hive.ql.exec.JobDebugger$TaskInfoGrabber.run(JobDebugger.java:142) at java.lang.Thread.run(Thread.java:662) FAILED: Execution Error, return code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask MapReduce Jobs Launched: Job 0: Map: 1 Reduce: 1 HDFS Read: 0 HDFS Write: 0 FAIL Total MapReduce CPU Time Spent: 0 msec Thank you ! Regards
