create table t1 (id number,  
                 version number,  
                 val varchar2(20),  
                 constraint t1_pk primary key (id, version))

insert into t1 (id, version, val)  
select 1 id, 0 version, 'A_1' val from dual union all  
select 2 id, 0 version, 'B_1' val from dual union all  
select 1 id, 1 version, 'A_2' val from dual union all  
select 3 id, 0 version, 'B_1' val from dual

commit

CREATE MATERIALIZED VIEW LOG ON t1  
LOGGING   
WITH SEQUENCE, ROWID, (val)  
INCLUDING NEW VALUES

create materialized view t1_latest 
refresh fast on commit 
as 
  select id, 
         max(version) latest_version 
  from   t1 
  group by id

select * from t1_latest

drop materialized view t1_latest

drop table t1