Showing posts with the label hadoop cluster setup

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SQL Interview Success: Unlocking the Top 5 Frequently Asked Queries

 Here are the five top commonly asked SQL queries in the interviews. These you can expect in Data Analyst, or, Data Engineer interviews. Top SQL Queries for Interviews 01. Joins The commonly asked question pertains to providing two tables, determining the number of rows that will return on various join types, and the resultant. Table1 -------- id ---- 1 1 2 3 Table2 -------- id ---- 1 3 1 NULL Output ------- Inner join --------------- 5 rows will return The result will be: =============== 1  1 1   1 1   1 1    1 3    3 02. Substring and Concat Here, we need to write an SQL query to make the upper case of the first letter and the small case of the remaining letter. Table1 ------ ename ===== raJu venKat kRIshna Solution: ========== SELECT CONCAT(UPPER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, 2))) AS capitalized_name FROM Table1; 03. Case statement SQL Query ========= SELECT Code1, Code2,      CASE         WHEN Code1 = 'A' AND Code2 = 'AA' THEN "A" | "A

How to Setup Hadoop Cluster Top Ideas

Hadoop cluster setup in Centos Operating System explained in this post. So you can install CentOs either in your Laptop or in Virtual Machine. Hadoop Cluster Setup Process 9 Steps Process to Setup Hadoop Cluster Step 1:  Installing Sun Java on Linux. Commands to execute for the same: sudo apt-add-repository ppa:flexiondotorg/java sudo apt-get update sudo apt-get install sun-java6-jre sun-java6-plugin sudo update-java-alternatives -s java-6-sun Step 2:  Create Hadoop User. Commands to execute for the same: $sudo addgroup hadoop $sudo adduser —ingroup hadoop hduser Step 3:  Install SSH Server if not already present. Commands are: $ sudo apt-get install openssh-server $ su - hduser $ ssh-keygen -t rsa -P "" $ cat $HOME/.ssh/ >> $HOME/.ssh/authorized_keys Step 4:  Installing Hadoop. Commands for the same are: $wget $ cd /home/hduser $ tar xzf hadoop-0.