frameworks - Simple explanation of MapReduce? - Stack Overflow
2008年8月26日 · 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 …
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 …
2019年2月3日 · 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 …
Setting the number of map tasks and reduce tasks - Stack Overflow
2011年7月31日 · 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 …
Good MapReduce examples - Stack Overflow
2012年9月12日 · 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 …
mapreduce - How to optimize shuffling/sorting phase in a hadoop …
2015年12月10日 · 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 …
Difference between combiner and partitioner - Stack Overflow
2019年4月11日 · I am a newbie to MapReduce and I just can't figure out the difference in the partitioner and combiner. I know both run in the intermediate step between the map and …
What is the purpose of shuffling and sorting phase in the reducer …
2014年3月3日 · Then, the MapReduce job stops at the map phase, and the map phase does not include any kind of sorting (so even the map phase is faster). Tom White has been an Apache …
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 - hadoop map reduce secondary sorting - Stack …
2013年8月23日 · 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 …