I have a fast refreshable materialized view question.
At the moment, the issue is, I cannot do any maintenance on mview base tables (e.g. tables that have mview log defined on them).
Our materialized views consist of joins to join multiple tables together, and due to that mview log must be created with rowid (not possible via PK). Now the problem that thw rowid opposes - whenever I move base table rows (whatever method I use, table redefinition perhaps), then my mviews are not fast refreshable any more, and since complete refresh takes more time to just drop and recreate it, then I have used drop/recreate approach, but this does mean downtime, since mview objects are missing from data dictionary for a certain amount of time.

I am curious, will there (23c) be any materialized view improvements compared to 19c ?
Curious about mview fast refresh using PK when mview consists JOIN operators. At the moment, fast refresh is only possible with rowid's when mview consists JOIN operators.

Or, if there is no such improvements done yet, what are future views regarding this issue - will there be hope that somedays this will be done. I mean in technical point of view, is it really tht difficult to implement. I mean the PK vs rowid - yes these both are different things, but share the same purpose. With PK, you only have that extra index access time cost in addition compared to rowid.

Raul

create table t1 (
  t1_pk int primary key,
  c1 int,
  c2 int
);

create table t2 (
  t2_pk int primary key,
  t1_fk references t1,
  c1 int,
  c2 int
);

create materialized view log 
  on t1 with rowid, primary key,
  sequence
  including new values;
  
create materialized view log 
  on t2 with rowid ( t1_fk ),
  sequence
  including new values;
  
create materialized view mv 
refresh fast on commit
as
  select count(*) c
  from   t1, t2
  where  t1_pk = t1_fk;
  
insert into t1 values ( 1, 1, 1 );
insert into t2 values ( 1, 1, 2, 2 );
insert into t2 values ( 2, 1, 3, 3 );
commit;
select * from mv;
/*
         C
----------
         2
*/
select rowid from t2;
/*
ROWID             
------------------
AAAsfpAAcAAACDuAAA
AAAsfpAAcAAACDuAAB
*/

alter table t2 
  move online;

select rowid from t2;
/*
ROWID             
------------------
AAAsfzAAcAAAv97AAA
AAAsfzAAcAAAv97AAB
*/

insert into t2 values ( 4, 1, 3, 3 );
commit;
select * from mv;
/*
         C
----------
         3
*/
select last_refresh_type, staleness 
from   user_mviews
where  mview_name = 'MV';
/*
LAST_REF STALENESS          
-------- -------------------
FAST     FRESH  
*/