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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.
Syntax
Here is the syntax of the GetHour() function.
grunt> GetHour(datetime)
Example
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.
date.txt
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; (1989-09-26T09:00:00.000+05:30) (1980-06-20T10:22:00.000+05:30) (1990-12-19T03:11:44.000+05:30)
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; (1989-09-26T09:00:00.000+05:30,9) (1980-06-20T10:22:00.000+05:30,10) (1990-12-19T03:11:44.000+05:30,3)