August 30, 2015
What is HDFS Federation? Namenode is responsible for the successful operation of HDFS. Namenode holds the entire metadata of HDFS, which includes information about files and […]
August 26, 2015
Reading A File From HDFS – Java Program In this last post we saw how to write a file to HDFS by writing our own Java […]
August 23, 2015
Writing A File To HDFS – Java Program Writing a file to HDFS is very easy, we can simply execute hadoop fs -copyFromLocal command to copy […]
August 16, 2015
What is Speculative Execution? Sometimes you will notice that a Job which has 3 input splits executed 4 mappers and killed the 4th mapper. The job […]
August 11, 2015
Changing Number Of Reducers In this blog post we saw how we can change the number of mappers in a MapReduce execution. In this post, we […]
August 9, 2015
Changing Number Of Mappers Number of mappers always equals to the Number of splits. Having said that it is possible to control the number of splits […]
August 4, 2015
InputSplit vs Block The central idea behind MapReduce is distributed processing and hence the most important thing is to divide the dataset in to chunks and […]
August 1, 2015
HDFS Block Placement Policy When a file is uploaded in to HDFS it will be divided in to blocks. HDFS will have to decide where to […]
