Apache Pig - GetHour()


This function accepts a date-time object as parameter and returns the current hour of the current day of a given date-time object.


Here is the syntax of the GetHour() function.

grunt> GetHour(datetime)


Assume that there is a file named date.txt in the HDFS directory /pig_data/ as shown below. This file contains the date-of-birth details of a particular person, id, date, and time.


001,1989/09/26 09:00:00
002,1980/06/20 10:22:00
003,1990/12/19 03:11:44

And, we have loaded this file into Pig with a relation named date_data as shown below.

grunt> date_data = LOAD 'hdfs://localhost:9000/pig_data/date.txt' USING PigStorage(',')
   as (id:int,date:chararray);

Following is an example of the GetHour() function. The GetHour() function will retrive the hour of the day from the given Date-Time object. Therefore, first of all, let’s generate the Date-Time objects of all employees using todate() function.

grunt> todate_data = foreach date_data generate ToDate(date,'yyyy/MM/dd HH:mm:ss')
   as (date_time:DateTime );
grunt> Dump todate_data;  

Let us now get the hour from the birth time of each employee using GetDay() function and store it in the relation named gethour_data.

grunt> gethour_data = foreach todate_data generate (date_time), GetHour(date_time);

Now verify the contents of the getday_data relation using the Dump operator as shown below.

grunt> Dump gethour_data;