我以cloudera网站为例编写了一个用于解析文件的自定义serde
http://blog.cloudera.com/blog/2012/12/how-to-use-a-serde-in-apache-hive/
这似乎是一个很好的例子，但当我用自定义serde创建表时

ADD JAR <path-to-hive-serdes-jar>;
CREATE EXTERNAL TABLE tweets (
  id BIGINT,
  created_at STRING,
  source STRING,
  favorited BOOLEAN,
  retweeted_status STRUCT<
    text:STRING,
    user:STRUCT<screen_name:STRING,name:STRING>,
    retweet_count:INT>,
  entities STRUCT<
    urls:ARRAY<STRUCT<expanded_url:STRING>>,
    user_mentions:ARRAY<STRUCT<screen_name:STRING,name:STRING>>,
    hashtags:ARRAY<STRUCT<text:STRING>>>,
  text STRING,
  user STRUCT<
    screen_name:STRING,
    name:STRING,
    friends_count:INT,
    followers_count:INT,
    statuses_count:INT,
    verified:BOOLEAN,
    utc_offset:INT,
    time_zone:STRING>,
  in_reply_to_screen_name STRING
) 
PARTITIONED BY (datehour INT)
ROW FORMAT SERDE 'com.cloudera.hive.serde.JSONSerDe'
LOCATION '/user/flume/tweets';

它执行得非常好，但当我这样做

select * from tweets;

我什么也没有得到，所以我想知道我是否可以在调试模式下运行配置单元，看看它在哪里失败