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From "Aruna Babu (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-3558) UDF LEFT(string,position) to HIVE
Date Tue, 09 Oct 2012 11:52:02 GMT
Aruna Babu created HIVE-3558:
--------------------------------

             Summary: UDF  LEFT(string,position) to HIVE
                 Key: HIVE-3558
                 URL: https://issues.apache.org/jira/browse/HIVE-3558
             Project: Hive
          Issue Type: New Feature
          Components: UDF
    Affects Versions: 0.9.0
            Reporter: Aruna Babu
            Priority: Minor
             Fix For: 0.10.0



Introduction


	UDF (User Defined Function) to obtain the left most 'n' characters from a string in  HIVE.



Relevance

	Current releases of Hive lacks a function which would returns the leftmost len characters
from the string str, or NULL if any argument is NULL.   
The function LEFT(string,length)  would return the leftmost 'n' characters from the string
, or NULL if any argument is NULL which would be useful while using HiveQL. This would find
its use  in all the technical aspects where the concept of strings are used.


Functionality :-

Function Name: LEFT(string,length) 
	 
Returns the leftmost length characters from the string  or NULL if any argument is NULL. 

Example: hive>SELECT LEFT('https://www.irctc.co.in',5);
        	-> 'https'

Usage :-
Case 1: To query a table to find details based on an https request
Table :-Transaction
Request_id|date|period_id|url_name

0001|01/07/2012|110001|https://www.irctc.co.in

0002|02/07/2012|110001|https://nextstep.tcs.com

0003|03/07/2012|110001|https://www.hdfcbank.com

0005|01/07/2012|110001|http://www.lmnm.co.in

0006|08/07/2012|110001|http://nextstart.com

0007|10/07/2012|110001|https://netbanking.icicibank.com

0012|21/07/2012|110001|http://www.people.co.in

0026|08/07/2012|110001|http://nextprobs.com

00023|25/07/2012|110001|https://netbanking.canarabank.com


Query : select * from transaction where LEFT(url_name,5)='https';


Result :-
0001|01/07/2012|110001|https://www.irctc.com
0002|02/07/2012|110001|https://nextstep.tcs.com  
0003|03/07/2012|110001|https://www.hdfcbank.com
0007|10/07/2012|110001|https://netbanking.icicibank.com
00023|25/07/2012|110001|https://netbanking.canarabank.com




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