MRS for Data structure table

Question

I need to various data structure table for MRS

Answer 1

A possible solution is create a materialized view and then a check constraint on the materialized view: this should work in a multiuser environment.
Example:
SQL> drop table t;
Table supprimee.
SQL>
SQL> create table t (
  2  x integer,
  3  y varchar2(10)
  4  );
Table creee.
SQL>
SQL> CREATE MATERIALIZED VIEW LOG on t
  2  WITH ROWID (x, y)
  3  including new values;
Journal de vue materialisee cree.
SQL>
SQL> CREATE MATERIALIZED VIEW t_mv
  2  REFRESH FAST ON COMMIT AS
  3  SELECT count(*) cnt
  4  FROM t;
Vue materialisee creee.
SQL>
SQL> ALTER TABLE t_mv
  2  ADD CONSTRAINT chk check(cnt<=1);
Table modifiee.
SQL>
SQL> insert into t values(1,'Ok');
1 ligne creee.
SQL> commit;
Validation effectuee.
SQL>
SQL> insert into t values(2,'KO');
1 ligne creee.
SQL> commit;
commit
ERREUR a la ligne 1 :
ORA-12008: erreur dans le chemin de regeneration de la vue materialisee
ORA-02290: violation de contraintes (TEST.CHK) de verification