Oracle 12.2 聯機重定義使用VPD策略的表並不修改表的任何列

下面的例子將演示如何聯機重定義使用VPD策略的表。這個例將禁用所有的觸發器而不修改表的列名或資料型別。原始表jy.employees的建立語句如下:

SQL> create table jy.employees(
  2  employee_id number(6) primary key,
  3  first_name varchar2(20),
  4  last_name varchar2(25)
  5  constraint emp_last_name_nn not null,
  6  email varchar2(25) constraint emp_email_nn not null,
  7  phone_number varchar2(20),
  8  hire_date date constraint emp_hire_date_nn not null,
  9  job_id varchar2(10) constraint emp_job_nn not null,
 10  salary number(8,2),
 11  commission_pct number(2,2),
 12  manager_id number(6),
 13  department_id number(4),
 14  constraint emp_salary_min check (salary > 0),
 15  constraint emp_email_uk unique (email)
 16  );

Table created.

使用下面的jy.auth_emp_dep_100函式來建立VPD策略

SQL> create or replace function jy.auth_emp_dep_100(
  2   schema_var in varchar2,
  3   table_var in varchar2
  4  )
  5  return varchar2
  6  as
  7   return_val varchar2 (400);
  8   unm varchar2(30);
  9   begin
 10    select user into unm from dual;
 11    if (unm = 'jy') then
 12     return_val := null;
 13    else
 14     return_val := 'department_id = 100';
 15    end if;
 16    return return_val;
 17   end auth_emp_dep_100;
 18  /

Function created.

執行dbms_rls_add_policy過程來對原始表jy.employees表使用jy.auth_emp_dep_100函式來指定VPD策略

SQL> begin
  2  dbms_rls.add_policy(
  3    object_schema => 'jy',
  4    object_name => 'employees',
  5    policy_name => 'employees_policy',
  6    function_schema => 'jy',
  7    policy_function => 'auth_emp_dep_100');
  8  end;
  9  /

PL/SQL procedure successfully completed.

在這個例子中，表jy.employees表重定義後將會禁用所有的觸發器。注意重定義將不會修改列名或資料型別。因此在執行start_refef_table過程時copy_vpd_opt引數設定為dbms_redefinition.cons_vpd_auto。

1.用要執行聯機重定義操作的使用者登入資料庫

SQL> conn jy/jy@jypdb
Connected.

2.驗證原始表是否可以執行聯機重定義

SQL> begin
  2   dbms_redefinition.can_redef_table('hr','employees',DBMS_REDEFINITION.CONS_USE_PK);
  3  end;
  4  /

PL/SQL procedure successfully completed.

3.建立中間表jy.int_employees

SQL> create table jy.int_employees(
  2   employee_id number(6),
  3   first_name varchar2(20),
  4   last_name varchar2(25),
  5   email varchar2(25),
  6   phone_number varchar2(20),
  7   hire_date date,
  8   job_id varchar2(10),
  9   salary number(8,2),
 10   commission_pct number(2,2),
 11   manager_id number(6),
 12   department_id number(4));

Table created.

4.開始聯機重定義操作

SQL> begin
  2  dbms_redefinition.start_redef_table(
  3  uname => 'jy',
  4  orig_table => 'employees',
  5  int_table => 'int_employees',
  6  col_mapping => NULL,
  7  options_flag => DBMS_REDEFINITION.CONS_USE_PK,
  8  orderby_cols => NULL,
  9  part_name => NULL,
 10  copy_vpd_opt => DBMS_REDEFINITION.CONS_VPD_AUTO);
 11  end;
 12  /

PL/SQL procedure successfully completed.

當copy_vpd_opt引數被設定為dbms_redefinition.cons_vpd_auto時，只有表的所有者與呼叫聯機重定義操作的使用者可以在聯機重定義期間訪問該表。col_mapping引數設定為NULL。當copy_vpd_opt引數設定為dbms_redefinition.cons_vpd_auto時，col_mapping引數必須設定為NULL或'*'。

5.複製依賴物件

SQL> declare
  2  num_errors pls_integer;
  3  begin
  4  dbms_redefinition.copy_table_dependents(
  5  uname => 'jy',
  6  orig_table => 'employees',
  7  int_table => 'int_employees',
  8  copy_indexes => DBMS_REDEFINITION.CONS_ORIG_PARAMS,
  9  copy_triggers => TRUE,
 10  copy_constraints => TRUE,
 11  copy_privileges => TRUE,
 12  ignore_errors => FALSE,
 13  num_errors => num_errors);
 14  end;
 15  /

PL/SQL procedure successfully completed.

6.對中間表禁用所有的觸發器

SQL> alter table jy.int_employees disable all triggers;

Table altered.

7.可選操作同步中間表

SQL> begin
  2  dbms_redefinition.sync_interim_table(
  3  uname => 'jy',
  4  orig_table => 'employees',
  5  int_table => 'int_employees');
  6  end;
  7  /

PL/SQL procedure successfully completed.

8.完成聯機重定義操作

SQL> begin
  2  dbms_redefinition.finish_redef_table(
  3  uname => 'jy',
  4  orig_table => 'employees',
  5  int_table => 'int_employees');
  6  end;
  7  /

PL/SQL procedure successfully completed.

9.等待任何查詢中間表的語句執行完成後將其刪除

SQL> drop table jy.int_employees;
Table dropped

到此重定義操作就完成了。