SQL Return the record where the value in a column have changed

I have data in Hive table which look something like this -

VIN	Mode	event	Start	End
ABC123456789	Mode 1	Deauthorized	01/01/2010 00:00:00	05/05/2014 14:54:54
ABC123456789	Mode 1	Deauthorized	05/05/2014 14:54:54	05/13/2014 19:09:51
ABC123456789	Mode 1	Deauthorized	05/13/2014 19:09:51	11/13/2014 22:26:32
ABC123456789	Mode 1	Authorized	11/13/2014 22:26:32	11/13/2014 22:31:00
ABC123456789	Mode 1	Authorized	11/13/2014 22:31:00	11/14/2014 01:23:56
ABC123456789	Mode 2	Deauthorized	11/14/2014 01:23:56	11/18/2014 19:38:51
ABC123456789	Mode 2	Deauthorized	11/18/2014 19:38:51	11/18/2014 19:38:54
ABC123456789	Mode 2	Deauthorized	11/18/2014 19:38:54	11/18/2014 20:07:52
ABC123456789	Mode 2	Authorized	11/18/2014 20:07:52	12/17/2014 19:22:50
ABC123456789	Mode 2	Authorized	12/17/2014 19:22:50	02/25/2015 20:03:44
ABC123456789	Mode 2	Authorized	02/25/2015 20:03:44	02/25/2015 20:03:48
ABC123456789	Mode 3	Authorized	02/25/2015 20:03:48	02/25/2015 20:14:05
ABC123456789	Mode 3	Deauthorized	02/25/2015 20:14:05	02/25/2015 20:14:29
ABC123456789	Mode 3	Deauthorized	02/25/2015 20:14:29	02/25/2015 20:40:21

I would like to get a summarized data where the value in event column has changed from previous value. The data points are in ascending order of the Start timestamp. I tried window function but it didn't work for me. The result would look similar to what I have shown in below table. Can you suggest any optimized solution for this?

VIN	Mode	event	Start	End
ABC123456789	Mode 1	Deauthorized	01/01/2010 00:00:00	05/05/2014 14:54:54
ABC123456789	Mode 1	Authorized	11/13/2014 22:26:32	11/13/2014 22:31:00
ABC123456789	Mode 2	Deauthorized	11/14/2014 01:23:56	11/18/2014 19:38:51
ABC123456789	Mode 2	Authorized	11/18/2014 20:07:52	12/17/2014 19:22:50
ABC123456789	Mode 3	Deauthorized	02/25/2015 20:14:05	02/25/2015 20:14:29

Solution

You can use lag():

select t.*
from (select t.*, 
             lag(event) over (partition by vin order by start) as prev_event
      from t
     ) t
where prev_event is null or prev_event <> event;

This looks at the changes by time and vin. I'm not sure if the mode is relevant too. If so, add it to the partition by.