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Editor to share with you an example of hive join null pointer exception analysis, I believe that most people do not know much about it, so share this article for your reference, I hope you will learn a lot after reading this article, let's go to know it!

2015-07-28 10 0%Ended Job 0315 Stage-2 map = 100%, reduce = 0%Ended Job = job_1437720498561_1035 with errorsError during job Obtaining debugging information...Examining task ID: task_1437720498561_1035_m_000000 (and more) from job job_1437720498561_1035Task with the most failures (4):-Task ID: task_1437720498561_1035_m_000000URL: http://0.0.0.0:8088/taskdetails.jsp?jobid=job_1437720498561_1035&tipid=task_1437720498561_1035_m_000000-----Diagnostic Messages for this Task:Error: java.lang.RuntimeException: java.lang.NullPointerException at Org.apache.hadoop.hive.ql.exec.mr.ExecMapper.map (ExecMapper.java:172) at org.apache.hadoop.mapred.MapRunner.run (MapRunner.java:54) at org.apache.hadoop.mapred.MapTask.runOldMapper (MapTask.java:453) at org.apache.hadoop.mapred.MapTask.run (MapTask.java:343) at org.apache.hadoop.mapred.YarnChild$2.run (YarnChild.java:163) At java.security.AccessController.doPrivileged (Native Method) at javax.security.auth.Subject.doAs (Subject.java:415) at org.apache.hadoop.security.UserGroupInformation.doAs (UserGroupInformation.java:1657) at org.apache.hadoop.mapred.YarnChild.main (YarnChild.java:158) Caused by: java.lang.NullPointerException at org.apache.hadoop.hive.ql.exec.MapJoinOperator.loadHashTable (MapJoinOperator.java:286) at org. Apache.hadoop.hive.ql.exec.MapJoinOperator.cleanUpInputFileChangedOp (MapJoinOperator.java:313) at org.apache.hadoop.hive.ql.exec.Operator.cleanUpInputFileChanged (Operator.java:1069) at org.apache.hadoop.hive.ql.exec.Operator.cleanUpInputFileChanged (Operator.java:1073) at org.apache.hadoop.hive.ql.exec.Operator.cleanUpInputFileChanged (Operator.java:1073) at org.apache.hadoop.hive.ql.exec.MapOperator. Process (MapOperator.java:501) at org.apache.hadoop.hive.ql.exec.mr.ExecMapper.map (ExecMapper.java:163)... 8 moreFAILED: Execution Error Return code 2 from org.apache.hadoop.hive.ql.exec.mr.MapRedTask

If NullPointerException occurs during hive join operation, please execute set hive.auto.convert.join=false

Setting the value of hive.auto.convert.join to true,hive will automatically use MapJoin when the size of the table matches the setting.

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