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
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.