Where does oracle store my object instances? - oracle

Question

I've created the following two object types :
create or replace type person_typ as object (
person# varchar(10)
) not final;
create or replace type salesperson_typ under person_typ (
salesperson# varchar(10),
sSurname varchar(10),
sForename varchar(10),
dateOfBirth date
);
create table person_tab of person_typ (
person# primary key
);
And I've inserted a row using :
insert into person_tab
values (salesperson_typ('p1','s1', 'Jones', 'John', sysdate));
Which I can retrieve using the following :
select
treat(value(s) as salesperson_typ).person# as person_number,
treat(value(s) as salesperson_typ).sSurname as sSurname
from
person_tab s
;
However, if I look at person_tab I only see the following :
SQL> select * from person_tab;
PERSON#
----------
p1
I'm curious, where does the salesperson specific data get stored? I was almost expecting to find a salesperson table, but I can't find anything obvious.

Answer 1

Your object is stored invisibly in the same table.
You can check columns by querying USER_TAB_COLS:
SELECT *
FROM user_tab_cols
WHERE table_name = 'PERSON_TAB';
Then you can then use the column names* you just discovered in a query (except SYS_NC_ROWINFO$, that throws an error for me).
SELECT SYS_NC_OID$
,SYS_NC_TYPEID$
--,SYS_NC_ROWINFO$
,PERSON#
,SYS_NC00005$
,SYS_NC00006$
,SYS_NC00007$
,SYS_NC00008$
FROM PERSON_TAB;
Note*
You should not use these column names in any application because they are internal and subject to change in future patches/releases.