json - 在配置单元中配置对象时出错

Question

我正在尝试使用推文和 hadoop 中的配置单元制作一个情感分析项目。我在 tweets json 格式之上创建了一个表，我可以在查询 SELECT * FROM TWEETS 后查看推文；然后我创建了以下 View ，但这不是在查询中检索数据 Select * from tweet_simple;

hive> CREATE VIEW tweets_simple AS
> SELECT
>   id,
>   cast ( from_unixtime( unix_timestamp(concat( '2014 ', substring(created_at,5,15)), 'yyyy MMM dd hh:mm:ss')) as timestamp) ts,
>   text,
>   user.time_zone
> FROM tweets;
OK
Time taken: 0.949 seconds

hive> Select * from tweets_simple limit 10;


Total MapReduce jobs = 1
Launching Job 1 out of 1
Number of reduce tasks is set to 0 since there's no reduce operator
Starting Job = job_201503010134_0001, Tracking URL = http://master:50030/jobdetails.jsp?jobid=job_201503010134_0001
Kill Command = /usr/lib/hadoop/bin/hadoop job  -kill     job_201503010134_0001
Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 0
2015-03-01 02:21:28,124 Stage-1 map = 0%,  reduce = 0%
2015-03-01 02:22:25,083 Stage-1 map = 100%,  reduce = 100%
Ended Job = job_201503010134_0001 with errors
Error during job, obtaining debugging information...
Job Tracking URL: http://master:50030/jobdetails.jsp?jobid=job_201503010134_0001
Examining task ID: task_201503010134_0001_m_000002 (and more) from job     job_201503010134_0001


Task with the most failures(4):
-----
Task ID:
  task_201503010134_0001_m_000000

URL:
  http://master:50030/taskdetails.jsp?jobid=job_201503010134_0001&    tipid=task_201503010134_0001_m_000000
-----
Diagnostic Messages for this Task:
java.lang.RuntimeException: Error in configuring object
    at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:109)
    at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:75)
    at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:133)
    at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:413)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:332)
    at org.apache.hadoop.mapred.Child$4.run(Child.java:268)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:396)
    at         org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.jav    a:1438)
        at org.apache.hadoop.mapred.Child.main(Child.java:262)
Caused by: java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at             sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at     sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.ja

FAILED: Execution Error, return code 2 from     org.apache.hadoop.hive.ql.exec.MapRedTask
MapReduce Jobs Launched:
Job 0: Map: 1   HDFS Read: 0 HDFS Write: 0 FAIL
Total MapReduce CPU Time Spent: 0 msec

Answer 1

数据是 json 格式。你已经在数据之上创建了表，所以每次查询数据时，它都需要反序列化器将 josn 数据解释为 hive 支持的数据格式。所以在运行查询之前添加 jar 作为:

添加 JAR/usr/lib/hive/lib/hive-serdes-1.0-SNAPSHOT.jar；

这个 jar 有 JSONSerDe.class 反序列化 JSON 对象。