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From "Shravan Mahankali" <shravan.mahank...@catalytic.com>
Subject how to use hadoop in real life?
Date Mon, 06 Jul 2009 12:25:49 GMT
Hi Group,


Finally I have written a sample Mapred program, submitted this job to Hadoop
and got the expected results. Thanks to all of you!


Now I don't have an idea of how to use Hadoop in real life (am sorry if am
asking wrong question at wrong time.! (So, am right ;-))) :


1) If I re-submit my job, Hadoop responds with an error message saying:
org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory
hdfs://localhost:9000/user/root/impressions_output already exists

2) How to automatically execute Hadoop jobs? let's say I have set a cron job
which runs various Hadoop jobs at specified times. Is this the way we do in
Hadoop world?

3) Can I submit jobs to Hadoop from a different machine/ network/ domain?

4) I would like to generate reports from the data collected in the Hadoop.
How can I do that?

5) Am thinking of replacing data in my database with Hadoop and query Hadoop
for various information. Is this correct?

6) How can I access analyzed data in Hadoop from external world, external


NOTE: I would like to use Java for any of above implementations.


Thanks in advance,

Shravan Kumar. M 

Catalytic Software Ltd. [SEI-CMMI Level 5 Company]


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