Re: General questions about Map-Reduce
I got it ... Thanks to all Cheers, Duc -- View this message in context: http://www.nabble.com/General-questions-about-Map-Reduce-tp21399361p21461628.html Sent from the Hadoop core-user mailing list archive at Nabble.com.
Re: General questions about Map-Reduce
On Sun, Jan 11, 2009 at 9:05 PM, tienduc_dinh tienduc_d...@yahoo.comwrote: Is there any article which describes it ? There's also Tom White's in-progress Hadoop: The Definitive Guide: http://my.safaribooksonline.com/9780596521974 flip -- http://www.infochimps.org Connected Open Free Data
Re: General questions about Map-Reduce
On Sun, Jan 11, 2009 at 9:05 PM, tienduc_dinh tienduc_d...@yahoo.comwrote: Is there any article which describes it ? I'd also recommend Google's MapReduce whitepaper: http://labs.google.com/papers/mapreduce.html
General questions about Map-Reduce
hi, I have some questions about Map-Reduce that I'm not sure, hope that you guys can help me. - Does Map-Reduce support parallel writing/reading ? I think not because I don't find anything like that in the source code. And why the data of a input file are distributed on many data-nodes but the parallel concept isn't used. - What happens after the Map-Reduce operation ? I got the first example on http://hadoop.apache.org/core/docs/current/mapred_tutorial.html#Example%3A+WordCount+v1.0 So after the Map-Reduce operation we got Bye, 1 Goodbye, 1 Hadoop, 2 Hello, 2 World, 2 But how can I know that the input file will be written/read correctly on the file system ? Any help will be appreciated, thanks. Tien Duc Dinh -- View this message in context: http://www.nabble.com/General-questions-about-Map-Reduce-tp21399361p21399361.html Sent from the Hadoop core-user mailing list archive at Nabble.com.
Re: General questions about Map-Reduce
On Jan 11, 2009, at 5:50 AM, tienduc_dinh wrote: - Does Map-Reduce support parallel writing/reading ? Yes. The maps all read in parallel with each other and the reduces all write in parallel with each other. - What happens after the Map-Reduce operation ? The OutputFormat usually writes the output to HDFS. -- Owen
Re: General questions about Map-Reduce
- What happens after the Map-Reduce operation ? The OutputFormat usually writes the output to HDFS. Hi Owen, thanks for your help. Is there any article which describes it ? Regards, Tien Duc Dinh -- View this message in context: http://www.nabble.com/General-questions-about-Map-Reduce-tp21399361p21407657.html Sent from the Hadoop core-user mailing list archive at Nabble.com.
Re: General questions about Map-Reduce
On Jan 11, 2009, at 7:05 PM, tienduc_dinh wrote: Is there any article which describes it ? Please read the map/reduce tutorial: http://hadoop.apache.org/core/docs/current/mapred_tutorial.html -- Owen
