Questions tagged [combiners]
105 questions
0
votes
1 answer
Do Merge happen first or combiner happen first in MapReduce
Consider a WordCount problem for a MapReduce Program.
Let us consider Mapper Output is as follows:
Hello 1
World 1
Hello 1
Hadoop 1
Hello 1
Hadoop 1
It goes to partitioner( we specify for 2 as no of reducer,)
Now mapoutput get partition in 2…
user6441445
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- 3
0
votes
1 answer
Why combiner output records = 0?
I have multipleinput, so I have two mappers. Also I have one combiner:
class JoinCombiner extends MapReduceBase implements
Reducer {
@Override
public void reduce(TextPair key, Iterator values,
…
user3650408
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0 answers
How to combine vectors of different length in a cell array into matrix in SCILAB?
Is there any function in SCILAB that looks like
http://www.mathworks.com/matlabcentral/fileexchange/33453-catpad
?
I have a lot of *.csv with wind values of several cities in a region that I should study. But when I try to put the wind values for…
Alcides Neto
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- 1
0
votes
3 answers
Apache hadoop combiners
What are the use cases where combiners are apt and what are the use cases where the combiners are not apt. I am aware of the functionality of combiner but i am trying to understand different use cases where combiners make sense.
wandermonk
- 6,856
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0
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3 answers
Combiner Implementation and internal working
I want to use a combiner in my MR code say WordCount.
How should I implement it?
What sort of data is being passed to the reducer from the combiner?
It will be great if anyone of you can provide me codes of both Combiner as well as the Reducer.
It…
Aniruddha Sinha
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0 answers
My reducer does not reduce the data completely
I am using combiner along with mapper and reducer.
My mapper code is as below:
#!/usr/bin/env python
import sys
import datetime
def main():
for line in sys.stdin:
data = line.strip().split("\t")
if len(data) != 6:
…
Ankur Agarwal
- 23,692
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3 answers
A way to combine multiple ogg files into one
Could anyone give me an example code or point me in the right direction of how to combine multiple ogg files into one using C#?
Evenflow
- 21
- 2
0
votes
1 answer
Comparing pairs of data, combining only sometimes
I am using Spark. I have a JavaPairRDD of the form >.
I have basically checked to see if a phrase is in the page specified by the URL, resulting in the structure above.
Now, I have several overlapping phrases (i.e.…
Chris Chambers
- 1,367
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0
votes
0 answers
Hadoop Combiner Not Writing to Reducer
Everything works fine locally when I do as follows:
Cat data | mapper.py | sort | combiner.py | reducer.py but when I ran this in Hadoop - combiner keeps on running without sending any output to reducer. Finally job gets killed.
Showing…
user2090693
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0 answers
Combine properties in all subclasses to input into parent class for SWIFT?
class example { //parent class
var one:Int = 10 //i want all subclass variableOne to be added to this
var two:Int = 20 //i want all subclass variableTwo to be added to this
init () {
}
}
class subClassOne : example { …
DAMON GONZALEZ
- 11
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- 3
0
votes
1 answer
How to mention a Combiner in Oozie while using streaming jar
I have a streaming job that I am calling through Oozie. I am able to run this successfully with a mapper and reducer. But what I am failing to understand is, how do I pass the combiner. All my mapper, reducer and combiner are written in Python. Will…
Sayon M
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0
votes
5 answers
Combine 2 textbox contents with delimiter
I'm having a bit of an issue. Lets say I have 2 text boxes, one on the left with this content:
Win
Lose
Hello
Goodbye
And one on the right, with this information:
One
Two
Three
Four
Now, on button press, I want to combine these two text boxes with…
2JZIgnition
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0
votes
1 answer
I find lessc-like combinator/compiler for javascript
Is there any method or solution for javascript compilation and combination like with lessc? I need a cli command for merging javascripts into one file. Maybe is there any nodejs app for it? Earlier I used CodeKit on mac, and that could compress and…
Zsolt Takács
- 368
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0
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1 answer
Hadoop combiner : Using same reducer code as combiner in a word count mapreduce program?
This question from the certification body's practice test in particular, does not make sense to me. Can anyone help ?
Question :
Word count problem with mapper emitting key and value pairs where for each word as key, literal 1 is emitted as the…
user2961928
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- 2
0
votes
1 answer
Why in Hadoop reduce_input_records less than combine_output_records?
I run the example of WordCount with a combiner.
Here's the running result:
13/10/07 22:32:38 INFO mapred.JobClient: Map input records=20111076
13/10/07 22:32:38 INFO mapred.JobClient: Reduce shuffle bytes=467280
13/10/07 22:32:38 INFO…
user1453951
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