Hive创建空表，即使有很多文件 [英] Hive creates empty table, even there're plenty of file

问题描述

我将一些文件放入包含如下数据的hdfs（ / path / to / directory / ）中;

  63 EB44863EA74AA0C5D3ECF3D678A7DF59 
 62 FABBC9ED9719A5030B2F6A4591EDB180 
 59 6BF6D40AF15DE2D7E295EAFB9574BBF8 
  

全部命名为 _user_hive_warehouse_file_name_000XYZ_A 。这些文件已从其他hdfs下载。

我试图通过Hive创建外部表;

<$ p $ CREATE EXTERNAL TABLE users（
id int，
user string
）
ROW FORMAT DELIMITED FIELDS TERMINATED BY'\ t'
LOCATION'/ path / to / directory /';

据说;

  OK 
所用时间：0.098秒
  

select * from users; 返回空。

select count（1）from用户; 返回 0 。

Hive成功创建表，但始终为空。如果我把其他文件如another.txt包含上面提到的示例数据， select count（1）from users; 返回 3 。

我缺少什么，为什么表格是空的？

环境：

• JDK 7


• Hadoop 2.6.0


• Hive 0.14.0
  
• Ubuntu 14.04

解决方案

I认为您遇到了在 HIVE-6431 中进行外围讨论的问题。特别是，这个注释很重要：

默认情况下，hadoop中的FileInputFormat（它是各种格式的超类）会忽略文件名称以_或。开头，很难在配置单元中使用。

解决方法很可能避免使用以 _ 或开头的文件名。

I put some files into hdfs (/path/to/directory/) which contain data like following;

63  EB44863EA74AA0C5D3ECF3D678A7DF59
62  FABBC9ED9719A5030B2F6A4591EDB180
59  6BF6D40AF15DE2D7E295EAFB9574BBF8

All of them named as _user_hive_warehouse_file_name_000XYZ_A. These files had downloaded from another hdfs.

I'm trying to create external table via Hive;

CREATE EXTERNAL TABLE users(
id int,
user string
)
ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t'
LOCATION '/path/to/directory/';

It says;

OK
Time taken: 0.098 seconds

select * from users; returns empty.

select count(1) from users; returns 0.

Hive creates the table successfully, but it's always empty. If I put another file like another.txt, that contains the sample data mentioned above, select count(1) from users; returns 3.

What am I missing, why the table is empty?

Environment:

• JDK 7
• Hadoop 2.6.0
• Hive 0.14.0
• Ubuntu 14.04

解决方案

I think you are encountering an issue that is peripherally discussed in HIVE-6431. In particular, this comment is the important one:

By default, FileInputFormat(which is the super class of various formats) in hadoop ignores file name starts with "_" or ".", and hard to walk around this in hive codebase.

The workaround is probably to avoid using filenames that begin with _ or .

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