hi
    when i read the source of mapred, i find there're a lot of classes with
the same names between "org.apache.hadoop.mapreduce" and
"org.apache.hadoop.mapred", such as "org.apache.hadoop.mapreduce.Counters"
and "org.apache.hadoop.mapred.Counters", why does this happen? why not
define only one Counters instead? what is the difference between the two
packages "org.apache.hadoop.mapreduce" and "org.apache.hadoop.mapred"?

    thx
Lv Peng

org.apache.hadoop.mapreduce is a newer api. To avoid breaking backwards
compatibility the older api, org.apache.hadoop.mapred was preserved, and
the newer api was just given a new name.

Check out
http://www.slideshare.net/sh1mmer/upgrading-to-the-new-map-reduce-api

J

On Tue, 2011-04-26 at 20:17 +0800, 吕鹏 wrote:
> hi
>     when i read the source of mapred, i find there're a lot of classes
> with the same names between "org.apache.hadoop.mapreduce" and
> "org.apache.hadoop.mapred", such
> as "org.apache.hadoop.mapreduce.Counters" and
> "org.apache.hadoop.mapred.Counters", why does this happen? why not
> define only one Counters instead? what is the difference between the
> two packages "org.apache.hadoop.mapreduce" and
> "org.apache.hadoop.mapred"?
>
>
>     thx
>
>
>
>
> Lv Peng

"org.apache.hadoop.mapred" is the package for old API and "org.apache.hadoop.mapreduce" is the package for new API. Although the two APIs have similar functionality, the implementation is different. Hadoop is migrating from the old API to the new API.

Wantao
 
 
------------------ Original ------------------
From:  "吕鹏"<[EMAIL PROTECTED]>;
Date:  Tue, Apr 26, 2011 08:17 PM
To:  "mapreduce-user"<[EMAIL PROTECTED]>;

Subject:  what is the difference between the two packages "org.apache.hadoop.mapreduce"and "org.apache.hadoop.mapred"?

 
 hi    when i read the source of mapred, i find there're a lot of classes with the same names between "org.apache.hadoop.mapreduce" and "org.apache.hadoop.mapred", such as "org.apache.hadoop.mapreduce.Counters" and "org.apache.hadoop.mapred.Counters", why does this happen? why not define only one Counters instead? what is the difference between the two packages "org.apache.hadoop.mapreduce" and "org.apache.hadoop.mapred"?
 

    thx
Lv Peng

Will the two packages be merged together?

It's really a little confusing.
2011/4/27 Wantao <[EMAIL PROTECTED]>

> "org.apache.hadoop.mapred" is the package for old API and
> "org.apache.hadoop.mapreduce" is the package for new API. Although the two
> APIs have similar functionality, the implementation is different. Hadoop is
> migrating from the old API to the new API.
>
> Wantao
>
>
> ------------------ Original ------------------
> *From: * "吕鹏"<[EMAIL PROTECTED]>;
> *Date: * Tue, Apr 26, 2011 08:17 PM
> *To: * "mapreduce-user"<[EMAIL PROTECTED]>;
> *Subject: * what is the difference between the two packages
> "org.apache.hadoop.mapreduce"and "org.apache.hadoop.mapred"?
>
> hi
> when i read the source of mapred, i find there're a lot of classes with the
> same names between "org.apache.hadoop.mapreduce" and
> "org.apache.hadoop.mapred", such as "org.apache.hadoop.mapreduce.Counters"
> and "org.apache.hadoop.mapred.Counters", why does this happen? why not
> define only one Counters instead? what is the difference between the two
> packages "org.apache.hadoop.mapreduce" and "org.apache.hadoop.mapred"?
>
> thx
>
>
> Lv Peng
>

--
haitao.yao@Beijing

El 4/26/2011 12:12 PM, Wantao escribió:
> "org.apache.hadoop.mapred" is the package for old API and
> "org.apache.hadoop.mapreduce" is the package for new API. Although the
> two APIs have similar functionality, the implementation is different.
> Hadoop is migrating from the old API to the new API.
>
> Wantao
> ------------------ Original ------------------
> *From: * "吕鹏"<[EMAIL PROTECTED]>;
> *Date: * Tue, Apr 26, 2011 08:17 PM
> *To: * "mapreduce-user"<[EMAIL PROTECTED]>;
> *Subject: * what is the difference between the two packages
> "org.apache.hadoop.mapreduce"and "org.apache.hadoop.mapred"?
> hi
> when i read the source of mapred, i find there're a lot of classes
> with the same names between "org.apache.hadoop.mapreduce" and
> "org.apache.hadoop.mapred", such as
> "org.apache.hadoop.mapreduce.Counters" and
> "org.apache.hadoop.mapred.Counters", why does this happen? why not
> define only one Counters instead? what is the difference between the
> two packages "org.apache.hadoop.mapreduce" and "org.apache.hadoop.mapred"?
>
> thx
>
>
> Lv Peng
The MapReduce ´s next generation is been implemented on the new API?
Regards

--
Marcos Luís Ortíz Valmaseda
  Software Engineer (Large-Scaled Distributed Systems)
  University of Information Sciences,
  La Habana, Cuba
  Linux User # 418229
  http://about.me/marcosortiz

On Tue, Apr 26, 2011 at 10:56 AM, Marcos Ortiz <[EMAIL PROTECTED]> wrote:
> The MapReduce ´s next generation is been implemented on the new API?

It supports both APIs. The MapReduce runtime is effectively unchanged. -C

hi all

When I run "hadoop job -status xxx",Output the following some list.

Rack-local map tasks=124
Data-local map tasks=6

What is the difference between Rack-local map tasks and Data-local map
tasks?
--
[EMAIL PROTECTED]|Sam