hadoop - 无法在 Hive 中使用 JSON Serde

Question

这一切都是根据本指南:http://blog.cloudera.com/blog/2012/12/how-to-use-a-serde-in-apache-hive/

hive> ADD JAR /home/hadoop/hive-serdes-1.0-SNAPSHOT.jar;
Added /home/hadoop/hive-serdes-1.0-SNAPSHOT.jar to class path
Added resource: /home/hadoop/hive-serdes-1.0-SNAPSHOT.jar

在 /tmp/new 我有一个文件 abc.json 其中包含以下内容: http://pastie.org/9504218

CREATE EXTERNAL TABLE 命令运行正常，但不接收任何数据:

hive> 
    > 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 '/tmp/new';
OK
Time taken: 0.142 seconds

选择*:

hive> select * from tweets;
OK
Time taken: 0.392 seconds

这里可能发生了什么？

Answer 1

所以问题是您创建了一个带分区的外部表。但是您没有在 Hive 中添加分区，也没有以这种方式在 HDFS 中创建目录。

以下是您可以遵循的步骤:

1.) Run the create table statement.
2.) In the directory /tmp/new/ create a sub directory datehour=<some int value>, and then put your .json file inside this.
3.) Run alter table statement adding this partition to metadata:
    alter table tweets add partition(datehour=<some int value>);
4.) Now run the select statement.

希望对您有所帮助...!!!