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From Sanjay Subramanian <>
Subject Re: Merging different HDFS file for HIVE
Date Sat, 27 Jul 2013 01:23:42 GMT
We have a similar situation like this in production…for your case case I would propose the
following steps

1. Design a map reduce job (Job Output format - Text, Lzo, Snappy, your choice)
     Inputs to Mapper
     -- records from these three feeds
    Outputs from Mapper
     -- Key = <EMP1>   Value = <feed1~field1  field2  field6  field9>
     -- Key = <EMP1>   Value = <feed2~field5  field7  field10>
     -- Key = <EMP1>   Value = <feed3~field3  field4  field8>

   Reducer Output
     -- Key = <EMP1>   Value = <field1  field2  field3  field4  field5  field6  field7
 field8  field9  field10>

2. (Optional) If u use LZO then u will need to run LzoIndexer


4. ALTER TABLE ADD PARTITION (foo1 = , foo2 = ) LOCATION 'path/to/files'

From: Stephen Sprague <<>>
Reply-To: "<>" <<>>
Date: Friday, July 26, 2013 4:37 PM
To: "<>" <<>>
Subject: Re: Merging different HDFS file for HIVE

i like #2.

so you have three, say, external tables representing your three feed files. After the third
and final file is loaded then join 'em all together - maybe make the table partitioned for
one per day.

for example:

alter table final add partition (datekey=YYYYMMDD);
insert overwrite table final partition (datekey=YYYYMMDD)  select EMP_ID,f1,...,f10 from FF1
a join FF2 b on (a.EMP_ID=b.EMP_ID join FF3 c on (b.EMP_ID=c.EMP_ID)

Or a variation on #3.   make a view on the three tables which would look just like the select
statement above.

What do you want to optimize for?

On Fri, Jul 26, 2013 at 5:30 AM, Nitin Pawar <<>>
Option 1 ) Use pig or oozie, write a workflow and join the files to a single file
Option 2 ) Create a temp table for each of the different file and then join them to a single
table and delete temp table
Option 3 ) don't do anything, change your queries to look at three different files when they
query  about different files

Wait for others to give better suggestions :)

On Fri, Jul 26, 2013 at 4:22 PM, Ramasubramanian Narayanan <<>>

Please help in providing solution for the below problem... this scenario is applicable in
Banking atleast...

I have a HIVE table with the below structure...

Hive Table:
Field 10

For the above table, I will get the values for each feed in different file. You can imagine
that these files belongs to same branch and will get at any time interval. I have to load
into table only if I get all 3 files for the same branch. (assume that we have a common field
in all the files to join)

Feed file 1 :
Field 1
Field 2
Field 6
Field 9

Feed File2 :
Field 5
Field 7
Field 10

Feed File3 :
Field 3
Field 4
Field 8

Now the question is,
what is the best way to make all these files to make it as a single file so that it can be
placed under the HIVE structure.


Nitin Pawar

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