Aruna Babu created HIVE-3558:
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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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