Flashback Table

Question

All dependent objects are retrieved when you perform a Flashback Drop, just as the objects are all added to the Recycle Bin when the base table is dropped.
Emp is dependent on dept table , here i go
SQL> drop table dept cascade constraints
  2  /
Table dropped.
SQL> flashback table dept to before drop
  2  /
Flashback complete.
SQL> select * from dept
  2  /
    DEPTNO DNAME          LOC
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON
SQL> insert into emp values (7935,'JERRY','DBA',7782,sysdate,8000,null,50)
  2  /
1 row created.Above insertion is not validating its parent key why? I dropped the dept table and then flashbacked.The PK should also be flashbacked and it is..
SQL> alter table dept add primary key (deptno)
  2  /
alter table dept add primary key (deptno)
ERROR at line 1:
ORA-02260: table can have only one primary keySo whats wrong , dropping and flashbacking parent table can cause to dependent table references?
SQL> alter table emp add foreign key (deptno) references dept
  2  /
alter table emp add foreign key (deptno) references dept
ERROR at line 1:
ORA-02298: cannot validate (SCOTT.SYS_C005461) - parent keys not foundFlashingback to parentes table mess up the PK and FK.

Answer 1

This is expected behaviour. Your CASCADE CONSTRAINTS dropped the constraint on EMP before dropping the table DEPT. They are implemented as separate operations, and the drop of the constraint is not protected by flashback. Then dropping DEPT renamed the table and all its dependent objects including the primary key (remember what is going on here: from 10.x, DROP is re-implemented as a RENAME), and the flashback recovered them.
If you think about it, this is good behaviour: it would be absurd to have a constraint based on a relationship with a dropped table.