hadoop - 在HDFS上，我想显示以ORC格式存储的配置单元表的普通文本

Question

我已经使用orc格式将json数据帧保存在Hive中

jsonDF.write.format("orc").saveAsTable(hiveExamples.jsonTest)

现在，我需要在HDFS上将文件显示为普通文本。有没有办法做到这一点？

我使用了 hdfs dfs -text /path-of-table，但是它以ORC格式显示数据。

Answer 1

linux shell命令中有一个名为hive --orcfiledump的实用程序
要在ORC中查看HDFS文件的元数据，可以调用以下命令:

[@localhost ~ ]$ hive --orcfiledump <path to HDFS ORC file>;

要以纯文本格式查看 ORC文件的内容，可以使用 -d选项调用命令:

[@localhost ~ ]$ hive --orcfiledump -d <path to HDFS ORC file>;

举个例子:

hive> DESCRIBE FORMATTED orders_orc;
Location:  hdfs://localhost:8020/user/hive/warehouse/training_retail.db/orders_orc
# Storage Information        
SerDe Library:          org.apache.hadoop.hive.ql.io.orc.OrcSerde    
InputFormat:            org.apache.hadoop.hive.ql.io.orc.OrcInputFormat  
OutputFormat:           org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat

hive> exit;

[@localhost ~ ]$ hdfs dfs -ls /user/hive/warehouse/training_retail.db/orders_orc
Found 1 items
-rwxrwxrwx   1 training hive     163094 2020-04-20 09:39 /user/hive/warehouse/training_retail.db/orders_orc/000000_0

[@localhost ~ ]$ hdfs dfs -tail /user/hive/warehouse/training_retail.db/orders_orc/000000_0
��+"%ў�.�b.����8V$tߗ��\|�?�xM��
                      *�ڣ�������!�2���_���Ͳ�V���
                                                     r�E(����~�uM�/&��&x=-�&2�T��o��JD���Q��m5��#���8Iqe����A�^�ێ"���@�t�w�m�A ���3|�����NL�Q����p�d�#:}S-D�Wq�_"����

[@localhost ~ ]$ hive --orcfiledump /user/hive/warehouse/training_retail.db/orders_orc/000000_0;
Structure for /user/hive/warehouse/training_retail.db/orders_orc/000000_0
File Version: 0.12 with HIVE_8732
20/04/20 10:19:58 INFO orc.ReaderImpl: Reading ORC rows from /user/hive/warehouse/training_retail.db/orders_orc/000000_0 with {include: null, offset: 0, length: 9223372036854775807}
Rows: 68883
Compression: ZLIB
Compression size: 262144
Type: struct<_col0:int,_col1:string,_col2:int,_col3:string>
....
File length: 163094 bytes
Padding length: 0 bytes
Padding ratio: 0%

[@localhost ~ ]$ hive --orcfiledump -d /user/hive/warehouse/training_retail.db/orders_orc/000000_0 | head -n 5
{"_col0":1,"_col1":"2013-07-25 00:00:00.0","_col2":11599,"_col3":"CLOSED"}
{"_col0":2,"_col1":"2013-07-25 00:00:00.0","_col2":256,"_col3":"PENDING_PAYMENT"}
{"_col0":3,"_col1":"2013-07-25 00:00:00.0","_col2":12111,"_col3":"COMPLETE"}
{"_col0":4,"_col1":"2013-07-25 00:00:00.0","_col2":8827,"_col3":"CLOSED"}
{"_col0":5,"_col1":"2013-07-25 00:00:00.0","_col2":11318,"_col3":"COMPLETE"}
     

您可以点击以下链接获取详细信息:
How to see contents of Hive orc files in linux