How to get min date and max date if results remain unchanged

I have an address SCD type 2 table but sometimes information entered remain the same I want to write a query that if information is unchanged, retain the previous begin data and set end date to max e.g

OBJID          BEGDA      ENDDA     HASHROW_COL RK 
83022088    2012-03-30  2012-10-28  e1-ef-a9-36 1 
83022088    2012-10-29  2013-09-07  63-69-e5-25 2 
83022088    2013-09-08  2014-08-30  e1-ef-a9-36 3
83022088    2014-08-31  2016-11-26  e1-ef-a9-36 4
83022088    2016-11-27  9999-12-31  e1-ef-a9-36 5

Notice that from rows 3 – 5 the HASHROW_COL remain the same.

Desired result:
OBJID          BEGDA       ENDDA    HASHROW_COL RK 
83022088    2012-03-30  2012-10-28  e1-ef-a9-36 1 
83022088    2012-10-29  2013-09-07  63-69-e5-25 2
83022088    2013-09-08  9999-12-31  e1-ef-a9-36 3

Query so far

select a.objid, a.hashrow_col, 
case when a.objid <> b.objid then b.begda
    when a.hashrow_col = b.hashrow_col and (b.begda - interval '1' day <= a.endda) then 
    a.begda  end,
case when a.objid <> b.objid then b.endda
    when (a.hashrow_col = b.hashrow_col) and (b.begda - interval '1' day <= a.endda) and b.endda > a.endda  
    then b.endda 
    end,
from
(select objid, begda, endda, HASHROW_COL, 
from OTABLE )  a
inner join 
(select objid, begda, endda, HASHROW_COL, 
from OTABLE) b
on
a.objid = b.objid
where 
and a.objid = '83022088' 
order by a.OBJID, a.BEGDA,  a.HASHROW_COL;

Solution

Here's a solution using the NORMALIZE function and the period data type.

We have to convert your start and end dates to a period. One gotcha with normalize to work is that consecutive end and start dates must overlap, that's why I've added 1 day to the end date (unless it's 9999-12-31').

select normalize on meets or overlaps objid,hashrow_col,duration from (
select
t.*,
period(begda, case when endda = '9999-12-31' then endda else endda +interval '1' DAY end) as duration
from
<your table> t) tt

Normalize and period are extremely powerful in the right circumstances.