On HDFS, I want to display normal text for a hive table stored in ORC format

问题

I have saved json dataframe in Hive using orc format

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

Now I need to display the file as a normal text on HDFS. Is there away to do this?

I have used hdfs dfs -text /path-of-table, but it displays the data in ORC format.

回答1:

From the linux shell command there is an utility called "hive --orcfiledump"

To see the metadata of an ORC file in HDFS you can invoke the command like:

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

To see the content of your ORC file in plain text you can invoke the command with -d option:

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

As an example:

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"}

You can follow this link for details:

How to see contents of Hive orc files in linux

I hope it can be helpful,

Regards.

来源：https://stackoverflow.com/questions/61305838/on-hdfs-i-want-to-display-normal-text-for-a-hive-table-stored-in-orc-format

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Hadoop