Oracle 11g新特性之--只读表（read only table）

Oracle 11g新特性之--只读表（read only table）

Oracle11g推出了一个新的特性，可以将table置于read only状态，处于该状态的table的不能执行DML操作和某些DDL操作。在Oracle11g之前的版本，只能将整个tablespace或者database置于read only状态。对于table的控制则只能通过权限来设定。

案例分析：

11:44:46 SCOTT@ test1 >select * from tab;TNAME                          TABTYPE  CLUSTERID------------------------------ ------- ----------BONUS                          TABLECREDIT_CLUSTER                 CLUSTERCREDIT_ORDERS                  TABLE            1DEPT                           TABLEEMP                            TABLEEMP1                           TABLE11:44:56 SCOTT@ test1 >select count(*) from emp1;  COUNT(*)----------        18Elapsed: 00:00:00.0411:45:12 SCOTT@ test1 >alter table emp1 read only;Table altered.11:51:46 SCOTT@ test1 >select read_only from user_tables where table_name='EMP1';REA---YES对只读表做DML:11:45:20 SCOTT@ test1 >insert into emp1 select * from emp where rownum=1;insert into emp1 select * from emp where rownum=1            *ERROR at line 1:ORA-12081: update operation not allowed on table "SCOTT"."EMP1"Elapsed: 00:00:00.0411:45:38 SCOTT@ test1 >delete from emp1;delete from emp1            *ERROR at line 1:ORA-12081: update operation not allowed on table "SCOTT"."EMP1"Elapsed: 00:00:00.0011:45:47 SCOTT@ test1 >update emp1 set sal=6000 where empno=7788;update emp1 set sal=6000 where empno=7788       *ERROR at line 1:ORA-12081: update operation not allowed on table "SCOTT"."EMP1"TRUNCATE TABLE:11:46:03 SCOTT@ test1 >truncate table emp1;truncate table emp1               *ERROR at line 1:ORA-12081: update operation not allowed on table "SCOTT"."EMP1"Elapsed: 00:00:00.09DROP TABLE:11:46:45 SCOTT@ test1 >drop table emp1;Table dropped.Elapsed: 00:00:00.7011:47:05 SCOTT@ test1 >show recycle;ORIGINAL NAME    RECYCLEBIN NAME                OBJECT TYPE  DROP TIME---------------- ------------------------------ ------------ -------------------EMP1             BIN$ComP5WftmQ7gUKjA+QgIyQ==$0 TABLE        2014-12-19:11:47:0411:47:52 SCOTT@ test1 >flashback table emp1 to before drop;Flashback complete.11:49:56 SCOTT@ test1 >select count(*) from emp1;  COUNT(*)----------        18        MOVE TABLE:        11:50:06 SCOTT@ test1 >alter table emp1 move;Table altered.Elapsed: 00:00:00.54压缩表：11:51:27 SCOTT@ test1 >alter table emp1 compress;Table altered.Elapsed: 00:00:00.0911:51:39 SCOTT@ test1 >alter table emp1 nocompress;Table altered.Elapsed: 00:00:00.16约束管理：11:52:53 SCOTT@ test1 >alter table emp1 add constraint fk_emp1 foreign key(deptno) references dept(deptno);Table altered.11:54:29 SCOTT@ test1 >alter table emp1 drop constraint fk_emp1;Table altered.11:54:47 SCOTT@ test1 >create index emp1_empno_ind on emp1(empno) tablespace indx;Index created.索引管理：11:55:17 SCOTT@ test1 >drop index emp1_empno_ind;Index dropped.配置read write：11:55:27 SCOTT@ test1 >alter table emp1 read write;Table altered.11:55:37 SCOTT@ test1 >select read_only from user_tables where table_name='EMP1';REA---NO