frameworks - Simple explanation of MapReduce? - Stack Overflow
Aug 26, 2008 · MapReduce is a method to process vast sums of data in parallel without requiring the developer to write any code other than the mapper and reduce functions. The map function …
Setting the number of map tasks and reduce tasks - Stack Overflow
Jul 31, 2011 · For each input split a map task is spawned. So, over the lifetime of a mapreduce job the number of map tasks is equal to the number of input splits. mapred.map.tasks is just a …
How does the MapReduce sort algorithm work? - Stack Overflow
MapReduce's use of input files and lack of schema support prevents the performance improvements enabled by common database system features such as B-trees and hash …
mapreduce - Does Spark internally use Map-Reduce? - Stack …
Feb 3, 2019 · Compared to MapReduce, which creates a DAG with two predefined stages - Map and Reduce, DAGs created by Spark can contain any number of stages. DAG is a strict …
mapreduce - What is Hive: Return Code 2 from …
I am getting: FAILED: Execution Error, return code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask While trying to make a copy of a partitioned …
mapreduce - How to optimize shuffling/sorting phase in a hadoop …
Dec 10, 2015 · mapreduce.shuffle.max.threads: Number of worker threads for copying the map outputs to reducers. mapreduce.reduce.shuffle.input.buffer.percent: How much of heap should …
mapreduce - hadoop map reduce secondary sorting - Stack …
Aug 23, 2013 · Can any one explain me how secondary sorting works in hadoop ? Why must one use GroupingComparator and how does it work in hadoop ? I was going through the link given …
mapreduce - Map / Reduce Tasks are failing extensively. Task Id ...
Nov 2, 2017 · I am new to Hadoop. My Laptop is 32GB, Core i5, 4 core processor. I have created multinode (3 data Node) apache hadoop cluster 2.7.4 on that by virtual machines. I have …
mapreduce - How does Hadoop perform input splits? - Stack …
5 Difference between block size and input split size. Input Split is logical split of your data, basically used during data processing in MapReduce program or other processing techniques. …
Good MapReduce examples - Stack Overflow
Sep 12, 2012 · MapReduce is a framework originally developed at Google that allows for easy large scale distributed computing across a number of domains. Apache Hadoop is an open …