Software, College Life and Clarity for successful careers
Suppose a 500 MB file containing store_id and daily_sales. Problem Statement: Find the sum of all times sales per store. store_id,date,daily_sales 1,12/01/2018,450 1,13/01/2018,500 1,14/01/2018,600 2,13/02/2018,400 2,14/02/2018,300 2,15/02/2018,600 … Solution: There are 3 steps involved in the MapReduce algorithm: Record Reader, Map, Shuffling, Sorting, Reducer Record Reader – Takes each line in the file and converts…
HDFS Basic Commands -t = sort by time -r = list in reverse -S = sort by size -R = recursively show all files under that particular directory(in this case, /user/hdpuser) -p = create if not exists hadoop fs -rmdir /user/hdpuser/dir1 (remove empty directory) hadoop fs -rm -R /user/hdpuser/dir2 (non empty directory) hadoop fs -mv…
MapReduce is a programming paradigm or an algorithm to process big data in a distributed environment. Traditional algorithms work when data is kept on single machine. For big data stored on multiple machines, MapReduce solves the problem of data processing. MapReduce Phases: Map and Reduce. Both take input and give output as Key-Value pairs =>…
“Biryani me elaichi ??!” – This is the feeling you must have got when suddenly the course changed from Big Data to Linux commands. Not to worry. Understanding and applying Linux commands is imperative and sometimes part of the daily routine in the day-to-day job as a Data Engineer. Shell scripting may also be required…
Read More “Post 9 – Linux Cheatsheet for Data Engineering” »
In this post, we will discuss different modes of Hadoop installation and their practical usage. Modes of Hadoop Installation: There are 3 modes of Hadoop installation: ▶ Local HDFS and YARN are not applicable in this mode. Ideal to test MapReduce logic. ▶ Pseudo Distributed It is Hadoop components on a single computer. HDFS, YARN…
We will be discussing interaction with HDFS using the command-line interface. For this, we can use two command prefaces: ➡ hadoop fs➡ hdfs dfs There are some basic differences between hadoop fs and hdfs dfs, but for all practical purposes of this post, both are the same. List files/directories ➡ hadoop fs -ls <dirname> (Directory…
Rack Awareness protects your highly crucial data from the forces of nature. What is a rack in Hadoop ? A Rack is a collection of servers (usually 10 or more) that are: ➡ Datanodes in a rack are physically close to each other(within the same data center or network switch) ➡ The intra-rack Datanodes are…
In the previous post, we discussed HDFS and how Hadoop handles Datanode failure. In this post, we will discuss how Hadoop handles Namenode failure. Hadoop 1.0 -> Namenode is a single point of failure. Failure handling is highly costly and time consuming due to recovery of edit logs. Hadoop 2.0 -> Introduction of Secondary Namenode…
HDFS stands for Hadoop Distributed File System. It is a distributed file system that is designed to store and manage large datasets across multiple computers in a cluster. It is highly fault-tolerant and can handle large amounts of data with high throughput, making it ideal for big data processing. HDFS architecture NN(NameNode) – Name Node stores the…
In this post, we will discuss what Apache Spark is and how it comes into play with Hadoop. Apache Spark is an independent general-purpose in-memory computing engine framework for big data processing. Therefore, Spark cannot be directly compared to Hadoop. The Hadoop framework provides distributed storage(HDFS), distributed processing(MapReduce), and distributed resource management. In contrast, Spark…