oracle课堂随笔----第二十九天

flashback database

SQL> shutdown immediate

SQL> startup mount

SQL> alter database flashback on; 数据库在归档模式下

SQL> show parameter db_flashback_retention_target

SQL> select OLDEST_FLASHBACK_TIME from v$flashback_database_log;

SQL> create table t1(x int);

SQL> insert into t1 values (1);

SQL> commit;

SQL> select dbms_flashback.get_system_change_number from dual;

SQL> truncate table t1;

SQL> create table after_truncate(x int); 其他正确操作

SQL> select OLDEST_FLASHBACK_TIME, OLDEST_FLASHBACK_SCN from v$flashback_database_log; 确认是否在恢复范围

SQL> shutdown abort

SQL> startup mount

SQL> flashback database to scn 1495195;

SQL> alter database open resetlogs;

SQL> select * from t1;

SQL> select * from after_truncate; 消失

移动数据

Sqlloader

单向数据装载（外面数据装进数据库）

SQL> create table t1(id int constraint t1_id_pk primary key, name varchar2(20), salary int constraint t1_salary_ck check(salary>0));

$ vi ~/loader.dat

100,"abc",1000

100,"def",2000

102,"xyz",-1000

em中常规导入，自动处理违反约束的记录

em中直接导入

SQL> select CONSTRAINT_NAME, STATUS from user_constraints where TABLE_NAME='T1';

SQL> select INDEX_NAME, STATUS from user_indexes where TABLE_NAME='T1';

SQL> alter table t1 enable validate constraint T1_SALARY_CK; 失败

SQL> @?/rdbms/admin/utlexpt1.sql

处理check约束：

SQL> alter table t1 enable validate constraint T1_SALARY_CK exceptions into exceptions;

SQL> select * from t1 where rowid in(select ROW_ID from exceptions);

SQL> update t1 set salary=abs(salary) where id=102;

SQL> truncate table exceptions;

SQL> alter table t1 enable validate constraint T1_SALARY_CK exceptions into exceptions;

处理pk约束：

SQL> alter table t1 disable novalidate constraint T1_ID_PK;

SQL> alter table t1 enable validate constraint T1_ID_PK exceptions into exceptions;

SQL> select * from t1 where rowid in(select ROW_ID from exceptions);

SQL> update t1 set id=101 where name='def';

SQL> truncate table exceptions;

SQL> alter table t1 enable validate constraint T1_ID_PK exceptions into exceptions;

SQL> select INDEX_NAME, STATUS from user_indexes where TABLE_NAME='T1';

外部表

映射（快捷方式）

oracle_datapump driver

unloading:

CREATE TABLE oe.inventories_xt

    ORGANIZATION EXTERNAL

    (

      TYPE ORACLE_DATAPUMP

      DEFAULT DIRECTORY DATA_PUMP_DIR

      LOCATION ('inv_xt.dmp')

    )

    AS SELECT * FROM oe.inventories;

SQL> delete oe.inventories_xt; 失败

loading:

CREATE TABLE oe.inventories_xt2

    (

      product_id          NUMBER(6),

      warehouse_id        NUMBER(3),

      quantity_on_hand    NUMBER(8)

    )

    ORGANIZATION EXTERNAL

    (

      TYPE ORACLE_DATAPUMP

      DEFAULT DIRECTORY DATA_PUMP_DIR

      LOCATION ('inv_xt.dmp')

    );

SQL> delete oe.inventories_xt2; 失败

优化

DB time = CPU time + Wait time