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From Prasanth Jayachandran <>
Subject Re: How to merge the output file when insert data into a table
Date Thu, 28 Aug 2014 16:44:25 GMT

If its an rcfile you can use "alter table tablename concatenate" to merge them into 1 file.
For text files, you can may have to reload these 2 files into another table with "Order By".
This will force one reducer to generate total ordering and thereby generating 1 output file.
But remember if the data size huge order by will take very long time. 


> On Aug 28, 2014, at 7:45 AM, 王洋 <> wrote:
> Hello,
>      I have two table ,one is stored as textfile for loading data from local data, the
other is stored as rcfile for compressing data。
>      when I execute the following sql two times
>      insert into table tablename1 select * from tablename2
>      I find that there are two files in the warehouse
>       hadoop fs -ls /user/hive/warehouse/tablename2/
>       Found 2 items
>      -rwxrwxrwt   3 root supergroup        423 2014-08-28 21:09 /user/hive/warehouse/tablename2/000000_0
>      -rwxrwxrwt   3 root supergroup        423 2014-08-28 21:11 /user/hive/warehouse/tablename2/000000_0_copy_1
>    I need to merge the two files to reduce the small file, is there have some way to
merge the files?  
>    thank you !

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