flashback技术之---flashback drop

简而言之，flashback drop就是将已经被drop的表从recycebin中恢复回来，表被drop后，实际上只是改了个名，并没有释放空间。

1. 启用和禁用recyclebin：

ALTER SESSION SET recyclebin = OFF;

ALTER SYSTEM SET recyclebin = OFF;

ALTER SESSION SET recyclebin = ON;

ALTER SYSTEM SET recyclebin = ON;

2.使用recyclebin进行flashback drop

SQL> create table test tablespace users as select * from dba_objects;

Table created.

SQL> select object_name,original_name,operation,type,ts_name,createtime,droptime from recyclebin;

no rows selected

SQL> drop table test;

Table dropped.

SQL> select object_name,original_name,operation,type,ts_name,createtime,droptime from recyclebin;

OBJECT_NAME                    ORIGINAL_N OPERATION TYPE       TS_NAME    CREATETIME          DROPTIME

------------------------------ ---------- --------- ---------- ---------- ------------------- -------------------

BIN$xRCsD3sxEqbgQAB/AQAqpw==$0 TEST       DROP      TABLE      USERS      2012-07-18:09:42:38 2012-07-18:09:42:48

SQL> FLASHBACK TABLE test TO BEFORE DROP  RENAME TO TEST_BAK;

Flashback complete.

SQL> select count(*) from test_bak;

  COUNT(*)

----------

     44940

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