Geek Languages

dfsadmin tool provide the commands to handle the safe mode.

The commands are-

1. hdfs dfsadmin -safemode get

This command will show if the name node is in safe mode or not
Output will be

Safe mode is ON (if namenode is in safe mode)
Safe mode is OFF (if namenode is not in safe mode)

2 .hdfs dfsadmin -safemode enter

 This command will take the namenode into the safe mode
 Output will be  -

 Safe mode is ON

3.hdfs dfsadmin -safemode leave

This command will force the namenode to come out of safe mode. It will be better if nameode is allowed to come out of safe mode itself.
Output will be -

Safe mode is OFF

CODE

#include <iostream>
using namespace std;

int addition (int a, int b)
{
  int r;
  r=a+b;
  return r;
}

int main ()
{
  int z;
  z = addition (5,3);
  cout << "The result is " << z;
}

for steps click on this link

http://geeklanguages.blogspot.in/2016/10/steps-to-install-hadoop-on-1.html

What is Apache Hive?
Apache Hive is a Data warehouse system which is built to work on Hadoop. It is used to querying and managing large datasets residing in distributed storage. Before becoming a open source project of Apache Hadoop, Hive was originated in Facebook. It provides a mechanism to project structure onto the data in Hadoop and to query that data using a SQL-like language called HiveQL.

What is HQL?
Hive defines a simple SQL-like query language to querying and managing large datasets called Hive-QL ( HQL ). It’s easy to use if you’re familiar with SQL Language. Hive allows programmers who are familiar with the language to write the custom MapReduce framework to perform more sophisticated analysis.

Uses of Hive:

1. The Apache Hive distributed storage.
2. Hive provides tools to enable easy data extract/transform/load (ETL).
3. It provides the structure on a variety of data formats.

Data Definition Language (DDL )

DDL statements are used to build and modify the tables and other objects in the database.
Example :CREATE, DROP, TRUNCATE, ALTER, SHOW, DESCRIBE Statements.

Data Manipulation Language (DML )

DML statements are used to retrieve, store, modify, delete, insert and update data in the database.
Example :LOAD, INSERT Statements.

Steps to install apache Pig

1. Download the tar file apache pig
2. Extract the tar file by

$ tar xvzf pig-0.15.0.tar.gz

3. Set the path of pig in bashrc file
4. Open the bashrc file by

$ sudo gedit .bashrc

5.paste these export lines in bashrc file at bottom

export PIG_HOME=/home/ratul/pig-0.15.0
export PATH=$PATH:/home/ratul/pig-0.15.0/bin
export PIG_CLASSPATH=$HADOOP_HOME/conf

6.run the command on terminal
for local mode

$ pig -x local

for mapreduce mode

$ pig -x mapreduce

 Steps to install Hive Database

$ tar xvzf apache-hive-1.2.1-bin

$ hive

Steps to Install hadoop on  ubuntu