Category Archives: Big Data Hadoop

Wow! Merge in Hive ? Yes , after the successful release of hive 2.2.X merge is also possible in hive now. Today I will walk you through one simple example that will clear merge concept in hive. What is Merge option in hive:- With Merge option we can perform record level insert,update and delete in […]

In this post , we will learn how to parse XML file using hive. I am using below xml file for this example. jmdbks@hadoop:~$ cat test.xml <test><name>Sumit Kumar</name><properties><age>29</age><sex>male</sex></properties></test> <test><name>Amit Kumar</name><properties><age>30</age><sex>male</sex></properties></test> <test><name>Aditya Kumar</name><properties><age>23</age><sex>male</sex></properties></test> <test><name>Priya Kumar</name><properties><age>24</age><sex>Female</sex></properties></test> <test><name>Rohan Kumar</name><properties><age>20</age><sex>male</sex></properties></test> <test><name>Nitish Kumar</name><properties><age>29</age><sex>male</sex></properties></test> jmdbks@hadoop:~$ Below are the Step by Step Procedure to parse XML file using hive . Step 1:- […]

(I)explode() and posexplode():- explode() takes in an array (or a map) as an input and outputs the elements of the array (map) as separate rows. Below example will help to understand explode() better. 1)Create example data set that having only one column  as Array<int>. beauty2955@hadoop:~$ cat array_exm1 100,200,300,500 400,200,201 300,45 101 2)create table and load array_exm1 into […]

  1)from_unixtime: This function converts the number of seconds from unix epoch (1970-01-01 00:00:00 UTC) to a STRING that represents the TIMESTAMP of that moment in the current system time zone in the format of “1970-01-01 00:00:00”. The following example returns the current date including the time. hive> SELECT FROM_UNIXTIME(UNIX_TIMESTAMP());   OK                                         2015–05–18 05:43:37 Time […]

Hive installation: 1.) search for apache hive-2.2.0 bin in google and download zar file (latest bin.tar.gz file) http://www-eu.apache.org/dist/hive/hive-2.2.0/ e.g. :- apache-hive-2.2.0-bin.tar.gz or download hive from linux command as below:– wget http://www-eu.apache.org/dist/hive/hive-2.2.0/apache-hive-2.2.0-bin.tar.gz 2.) extract file: tar -xvf <filename> e.g.:-tar -xvf apache-hive-2.2.0-bin.tar.gz mv apache-hive-2.2.0-bin hive2 3.) download mysqlconnector by using below command wget https://la-mirrors.evowise.com/mysql/Downloads/Connector-J/mysql-connector-java-5.1.45.tar.gz extract file : […]

HDFS commands 1)mkdir (Create a directory) hadoop fs –mkdir  /data 2)copyFromLocal(Copy a file or directory from Local to HDFS) If we want to copy file1 from local to HDFS inside directory /data then we have to use below command hadoop fs –copyFromLocal file1  /data/ Note: Can be used for copying multiple files, similar pattern files, […]