问题描述：创建物化视图时出现ORA-12054告警，如下所示：
数据库：oracle 19.12 64位
异常现象:
SQL> desc emp
 Name                                                  Null?    Type
 ----------------------------------------------------- -------- ------------------------------------
 EMPLOYEE_ID                                           NOT NULL NUMBER(6)
 FIRST_NAME                                                     VARCHAR2(9)
 LAST_NAME                                             NOT NULL VARCHAR2(25)
 EMAIL                                                 NOT NULL VARCHAR2(25)
 PHONE_NUMBER                                                   VARCHAR2(20)
 HIRE_DATE                                             NOT NULL TIMESTAMP(6)
 JOB_ID                                                NOT NULL VARCHAR2(12)
 SALARY                                                         NUMBER(8,2)
 COMMISSION_PCT                                                 NUMBER(2,2)
 MANAGER_ID                                                     NUMBER(6)
 DEPARTMENT_ID                                                  NUMBER(4)

SQL> select count(*) from emp;

  COUNT(*)
----------
        20
SQL> create materialized view v_emp
  2  refresh force on commit
  3  as
  4  select employee_id,first_name,last_name,email,phone_number,hire_date from emp;
select employee_id,first_name,last_name,email,phone_number,hire_date from emp
                                                                          *
ERROR at line 4:
ORA-12054: cannot set the ON COMMIT refresh attribute for the materialized view
说明：如上所示，ORA-12054告警异常重现.
异常原因：
创建物化视图的基表没有主键.
解决过程：
查emp表是否存在主键.
SQL> SELECT                                                                  
  2       col.column_name
  3  FROM
  4       user_constraints con,user_cons_columns col
  5  WHERE
  6       con.constraint_name=col.constraint_name and con.constraint_type='P'
  7       and col.table_name='EMP';

no rows selected
给emp表添加主键.
SQL> alter table emp add constraint pk_emp_employee_id primary key (employee_id);

Table altered.

SQL> SELECT                                                                  
  2       col.column_name
  3  FROM
  4       user_constraints con,user_cons_columns col
  5  WHERE
  6       con.constraint_name=col.constraint_name and con.constraint_type='P'
  7       and col.table_name='EMP';

COLUMN_NAME
--------------------
EMPLOYEE_ID
确定表emp存在主键后，再次创建物化视图，无异常发生.
SQL> create materialized view v_emp
  2  refresh force on commit
  3  as
  4  select employee_id,first_name,last_name,email,phone_number,hire_date from emp;

Materialized view created.

SQL> select segment_name,segment_type,segment_subtype,tablespace_name,bytes from user_segments where segment_name like '%PK_EMP_EMPLOYEE_ID%' or segment_name='V_EMP'

SEGMENT_NAME                        SEGMENT_TYPE       SEGMENT_SU TABLESPACE_NAME      BYTES
----------------------------------- ------------------ ---------- --------------- ----------
PK_EMP_EMPLOYEE_ID                  INDEX              ASSM       USERS                65536
SYS_C_SNAP$_5PK_EMP_EMPLOYEE_ID     INDEX              ASSM       USERS                65536
V_EMP                               TABLE              ASSM       USERS                65536
说明：如上所示，物化视图创建好后实则为实实在在的表，而且系统会自动产生名为SYS_C_SNAP$_5PK_EMP_EMPLOYEE_ID的索引，都会也会占用空间.这是与普通视图最大的区别.

SQL> update emp set email='aaaa' where employee_id=100;

1 row updated.

SQL> select * from v_emp where employee_id=100;

EMPLOYEE_ID FIRST_NAM LAST_NAME                 EMAIL                     PHONE_NUMBER         HIRE_DATE
----------- --------- ------------------------- ------------------------- -------------------- ------------------------------
        100 Steven    King                      SKING                     515.123.4567         17-JUN-11 12.00.00.000000 AM

SQL> commit;

Commit complete.

SQL> select * from v_emp where employee_id=100;

EMPLOYEE_ID FIRST_NAM LAST_NAME                 EMAIL                     PHONE_NUMBER         HIRE_DATE
----------- --------- ------------------------- ------------------------- -------------------- ------------------------------
        100 Steven    King                      aaaa                      515.123.4567         17-JUN-11 12.00.00.000000 AM
SQL> update v_emp set email='bbbb' where employee_id=100;
update v_emp set email='bbbb' where employee_id=100
       *
ERROR at line 1:
ORA-01732: data manipulation operation not legal on this view

说明：一旦提交更新主表emp相关信息后，物化视图v_emp同样也会更新信息.