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 …

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 …

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 …

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 …

Jan 9, 2009 · What scenarios would warrant the use of the "Map and Reduce" algorithm? Is there a .NET implementation of this algorithm?

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 …

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 …

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 …

Apr 22, 2020 · By default spark (2.4.4) use MapReduce.fileoutputcommitter.algorithm.version 1. I am trying it to change it to version 2. spark-UI and sparkCtx._conf.getAll() shows version 2 but …

Sep 25, 2013 · If you are using Hadoop Streaming, you can use the JobConf variables in a streaming job's mapper/reducer. As for the input file name of mapper, see the Configured …