Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Hadoop, mail # dev - MapReduce V1 vs MapReduce V2

Copy link to this message
MapReduce V1 vs MapReduce V2
Matt Fellows 2014-01-03, 10:19
I'm thoroughly confused about which API is the recent one, which is the old
one and which method I should be using to write MapReduce applications.

I'm under the impression that MRv2 is primarily driven by the
org.apache.hadoop.mapreduce.* packages and MRv1 is primarily driven by the
org.apache.hadoop.mapred.* packages.

I've been led to believe that MRv2 applications extend MapReduceBase and
implement Mapper, Reducer etc.
and conversely the MRv1 applications extend Mapper, Reducer directly.

However I can not find a canonical statement to back any of this up.
 What's more I keep finding conflicting statements about these, such as
"'Hadoop - the definitive guide' gives example in MRv2 format" but then I
look at the examples and they use org.apache.hadoop.mapreduce.* packages,
but extend Mapper and extend Reducer, not MapReduceBase...

Can someone either point me at a canonical resource or just confirm / deny
my assumptions?

Kind regards

[image: cid:1CBF4038-3F0F-4FC2-A1FF-6DC81B8B6F94]
 First Option Software Ltd
Signal House
Jacklyns Lane
SO24 9JJ
Tel: +44 (0)1962 738232
Mob: +44 (0)7710 160458
Fax: +44 (0)1962 600112
Web: www.b <http://www.fosolutions.co.uk/>espokesoftware.com<http://bespokesoftware.com/>


This is confidential, non-binding and not company endorsed - see full terms
at www.fosolutions.co.uk/emailpolicy.html
First Option Software Ltd Registered No. 06340261
Signal House, Jacklyns Lane, Alresford, Hampshire, SO24 9JJ, U.K.