Create Materialized View question

Question

Hi all,
I have a question about MV.
Toad creation wizard of a new snapshots (materialized view) on "Refresh Info" tab I set
Refresh mode: complete On demand
With: ROWID (I can't use primary key because on my table there isn't PK)
Writing teh query, next the Materialized View is successfully created and this is a toad script:
CREATE MATERIALIZED VIEW ASDF
TABLESPACE USERS
NOCACHE
LOGGING
NOCOMPRESS
NOPARALLEL
BUILD IMMEDIATE
REFRESH COMPLETE ON DEMAND
WITH PRIMARY KEY
AS
select CDA_PART, DES_PART, DES_MAT, CDA_APPART, CDA_PROVEN
from ldanapr01
where dat_end>(sysdate-1);Why is specified WITH PRIMARY KEY if I created the view with ROWID option?
Indeed if a drop a MV and directly run the create VM script above obtain error ORA-14012 table 'LDANAPR01' does not contain a primary key constraint.
So, if I modify the script in this way
CREATE MATERIALIZED VIEW ASDF
TABLESPACE USERS
NOCACHE
LOGGING
NOCOMPRESS
NOPARALLEL
BUILD IMMEDIATE
REFRESH COMPLETE ON DEMAND
WITH ROWID
AS
select CDA_PART, DES_PART, DES_MAT, CDA_APPART, CDA_PROVEN
from ldanapr01
where dat_end>(sysdate-1);the MV is successfully created!!
What is difference between WITH PRIMARY KEY and WITH ROW ID... and why Toad show always the created MV script as WITH PRIMARY KEY ?

Answer 1

>
WITH PRIMARY KEY is used to create a primary key materialized view i.e. the materialized view is based on the primary key of the master table instead of ROWID (for ROWID clause). PRIMARY KEY is the default option. To use the PRIMARY KEY clause you should have defined PRIMARY KEY on the master table or else you should use ROWID based materialized views.
Primary key materialized views allow materialized view master tables to be reorganized without affecting the eligibility of the materialized view for fast refresh.
Rowid materialized views should have a single master table and cannot contain any of the following:
* Distinct or aggregate functions
* GROUP BY Subqueries , Joins & Set operations
source : http://www.dbasupport.com/oracle/ora9i/mat_views2.shtml