java - 获取java.lang.NullPointerException hadoop map-reduce程序

Question

从db提取数据并加载到另一个表时出现以下错误:

15/07/01 04:23:15 INFO mapreduce.Job: Task Id : attempt_1434100146148_0014_m_000000_0, Status : FAILED
Error: java.lang.NullPointerException
    at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.initialize(MapTask.java:525)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:763)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
    at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:167)
    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:1557)
    at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)

Answer 1

谢谢Subba

上面的问题解决了。我的输入SQL查询中的列名有错误。我的查询是

select * from allTypes where **key** = ?;(correct) 
select * from allTypes where **id** = ?;(wrong ...no column as id)