Can one implement combiner and reducer separately?

0 votes

I was checking few hadoop projects on the internet and github. There, in many programs, I found that people have used reducer as combiner. One of the reason to do so might be because of the use case context or is it the only way to implement combiner? I mean, can I have implement combiner and reducer separately in a MapReduce program. 

Apr 10, 2018 in Big Data Hadoop by Shubham
• 12,270 points
199 views

1 answer to this question.

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
0 votes

Surely, you can use combiner separately along with reducer but, for implementing combiner you still be using reducer interface. Now, it is quite important for you to understand where combiner should be used. The primary goal of combiners is to optimize/minimize the number of key value pairs that will be shuffled across the network between mappers and reducers and thus to save as most bandwidth as possible.

You can consider combiner as mini reducer which is called several times during the map phase in order to reduce the set of key/value pairs that will be eventually sent to the reducer. This is the reason why combiner must implement the reduce interface or you can extend reducer class. 

answered Apr 10, 2018 by Ashish
• 2,630 points

Related Questions In Big Data Hadoop

0 votes
1 answer

How can I download only hdfs and not hadoop?

No, you cannot download HDFS alone because ...READ MORE

answered Mar 15, 2018 in Big Data Hadoop by nitinrawat895
• 9,070 points
54 views
0 votes
1 answer

How to create a FileSystem object that can be used for reading from and writing to HDFS?

Read operation on HDFS In order to read ...READ MORE

answered Mar 21, 2018 in Big Data Hadoop by nitinrawat895
• 9,070 points

edited Mar 21, 2018 by nitinrawat895 148 views
0 votes
1 answer
0 votes
1 answer
0 votes
1 answer

Hadoop Mapreduce word count Program

Firstly you need to understand the concept ...READ MORE

answered Mar 16, 2018 in Data Analytics by nitinrawat895
• 9,070 points
1,676 views
0 votes
1 answer

hadoop.mapred vs hadoop.mapreduce?

org.apache.hadoop.mapred is the Old API  org.apache.hadoop.mapreduce is the ...READ MORE

answered Mar 16, 2018 in Data Analytics by nitinrawat895
• 9,070 points
132 views
0 votes
10 answers

hadoop fs -put command?

copy command can be used to copy files ...READ MORE

answered Dec 7, 2018 in Big Data Hadoop by Sujay
8,140 views
0 votes
1 answer

Hadoop dfs -ls command?

In your case there is no difference ...READ MORE

answered Mar 16, 2018 in Big Data Hadoop by kurt_cobain
• 9,260 points
570 views
0 votes
1 answer
0 votes
1 answer

When is an identity mapper/reducer used?

1.One of the simplest example of Iterative ...READ MORE

answered Apr 3, 2018 in Big Data Hadoop by Ashish
• 2,630 points
747 views

© 2018 Brain4ce Education Solutions Pvt. Ltd. All rights Reserved.
"PMP®","PMI®", "PMI-ACP®" and "PMBOK®" are registered marks of the Project Management Institute, Inc. MongoDB®, Mongo and the leaf logo are the registered trademarks of MongoDB, Inc.