Why sys does not refresh fast ?

Question

Hi everyone.
The following test was made on a Windows XP Professional 2002 SP 2 box.
I don't understand why sys user does not perform a fast refresh on a materialized view. With others users it works fine. May be I am missing something.
This is my simple test case:
C:\>sqlplus "sys/sys as sysdba"
SQL*Plus: Release 9.2.0.1.0 - Production on Sun Nov 6 14:44:51 2005
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
SQL> create table my_objects as select * from user_objects;
Table created.
SQL> alter table my_objects add primary key(object_id);
Table altered.
SQL> create materialized view log on my_objects with primary key including new values;
Materialized view log created.
SQL> create materialized view mv_my_objects
2 refresh fast on demand
3 as select * from my_objects;
Materialized view created.
SQL> select count(*) from my_objects;
COUNT(*)
13535
SQL> select count(*) from mv_my_objects;
COUNT(*)
13535
SQL> delete from my_objects where rownum <=100;
100 rows deleted.
SQL> commit;
Commit complete.
SQL> select count(*) from mv_my_objects;
COUNT(*)
13535
SQL> select count(*) from my_objects;
COUNT(*)
13435
SQL> exec dbms_mview.refresh('mv_my_objects', 'F');
PL/SQL procedure successfully completed.
SQL> select count(*) from mv_my_objects;
COUNT(*)
13535
C:\>sqlplus scott/tiger
SQL*Plus: Release 9.2.0.1.0 - Production on Sun Nov 6 14:50:31 2005
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
SQL> create table my_objects as select * from user_objects;
Table created.
SQL> alter table my_objects add primary key(object_id);
Table altered.
SQL> create materialized view log on my_objects with primary key including new values;
Materialized view log created.
SQL> create materialized view mv_my_objects
2 refresh fast on demand
3 as select * from my_objects;
Materialized view created.
SQL> select count(*) from my_objects;
COUNT(*)
8
SQL> select count(*) from mv_my_objects;
COUNT(*)
8
SQL> delete from my_objects where rownum <=4;
4 rows deleted.
SQL> commit;
Commit complete.
SQL> select count(*) from mv_my_objects;
COUNT(*)
8
SQL> select count(*) from my_objects;
COUNT(*)
4
SQL> exec dbms_mview.refresh('mv_my_objects', 'F');
PL/SQL procedure successfully completed.
SQL> select count(*) from mv_my_objects;
COUNT(*)
4
SQL>

Answer 1

I agree, never create objects under sys schema. I noticed that behaviour just by accident, making some tests while reading the data warehousing manual.
It is more surprising the fact Oracle lets you create the log, and also throws a "PL/SQL procedure successfully completed" message when you use it.
Regards.