我们知道,在Oracle 10g中,drop table如果没有加 purge选项.实际数据并没有删除,因而没有释放表空间.

　　那么当被删除的对象占用了所有空间时，会发生什么? 相信看完以下测试,一切皆会明白

　　YXYUP@dbatest>selecttablespace_name,sum(bytes)/1024/1024 from dba_data_files where tablespace_name=’TBS’ group by tablespace_name;

　　TABLESPACE_NAME SUM(BYTES)/1024/1024

　　TBS 17

　　Elapsed: 00:00:00.02

　　YXYUP@dbatest>selectsegment_name,bytes/1024/1024,tablespace_name from user_segments;

　　SEGMENT_NAME BYTES/1024/1024 TABLESPACE_NAME

　　TEST_BAK 6 TBS

　　TEST01 6 TBS

　　Elapsed: 00:00:00.07

　　YXYUP@dbatest>createtable test02 tablespace tbs as select * from dba_objects;

　　create table test02 tablespace tbs as select * from dba_objects

　　*

　　ERROR at line 1:

　　ORA-01652: unable to extend temp segment by 128 in tablespace TBS

　　Elapsed: 00:00:00.73

　　YXYUP@dbatest>droptable test01;

　　Table dropped.

　　Elapsed: 00:00:00.04

　　YXYUP@dbatest>showrecyclebin;

　　ORIGINAL NAME RECYCLEBIN NAME OBJECT TYPE DROP TIME

　　TEST01 BIN$VPH4ibnKVd/gQAB/AQA0Nw==$0 TABLE 2008-08-21:14:56:55

　　YXYUP@dbatest>

　　YXYUP@dbatest>select* from tab;

　　TNAME TABTYPE CLUSTERID

　　BIN$VPH4ibnKVd/gQAB/AQA0Nw==$0 TABLE

　　TEST_BAK TABLE

　　Elapsed: 00:00:00.01

　　YXYUP@dbatest>createtable test02 tablespace tbs as select * from dba_objects;

　　Table created.

　　Elapsed: 00:00:00.84

　　YXYUP@dbatest>showrecyclebin;

　　YXYUP@dbatest>select* from tab;

　　TNAME TABTYPE CLUSTERID

　　TEST_BAK TABLE

　　TEST02 TABLE

　　Elapsed: 00:00:00.01

　　上面测试可以看出,当表空间空闲空间不足时,Oracle就会将recyclebin中的表给彻底删除,然后腾出空间来放要创建的新对象.

　　那么,如果recyclebin中有多个被drop的对象时,Oracle会怎么清理呢,是全部清除,还是怎样? 通过下面的测试我们行到答案.

　　YXYUP@dbatest>showrecyclebin;

　　YXYUP@dbatest>select* from tab;

　　TNAME TABTYPE CLUSTERID

　　TEST_BAK TABLE

　　TEST02 TABLE

　　Elapsed: 00:00:00.01

　　YXYUP@dbatest>droptable test02;

　　Table dropped.

　　Elapsed: 00:00:00.04

　　YXYUP@dbatest>droptable test_bak;

　　Table dropped.

　　Elapsed: 00:00:00.02

　　YXYUP@dbatest>select* from tab;

　　TNAME TABTYPE CLUSTERID

　　BIN$VPH4ibnLVd/gQAB/AQA0Nw==$0 TABLE

　　BIN$VPH4ibnMVd/gQAB/AQA0Nw==$0 TABLE

　　Elapsed: 00:00:00.01

　　YXYUP@dbatest>showrecyclebin;

　　ORIGINAL NAME RECYCLEBIN NAME OBJECT TYPE DROP TIME

　　TEST02 BIN$VPH4ibnLVd/gQAB/AQA0Nw==$0 TABLE 2008-08-21:15:14:43

　　TEST_BAK BIN$VPH4ibnMVd/gQAB/AQA0Nw==$0 TABLE 2008-08-21:15:14:51

　　YXYUP@dbatest>createtable test01 tablespace tbs as select * from dba_objects;

　　Table created.

　　Elapsed: 00:00:00.79

　　YXYUP@dbatest>select* from tab;

　　TNAME TABTYPE CLUSTERID

　　BIN$VPH4ibnMVd/gQAB/AQA0Nw==$0 TABLE

　　TEST01 TABLE

　　Elapsed: 00:00:00.01

　　YXYUP@dbatest>flashbacktable TEST02 to before drop ;

　　flashback table TEST02 to before drop

　　*

　　ERROR at line 1:

　　ORA-38305: object not in RECYCLE BIN

　　Elapsed: 00:00:00.00

　　YXYUP@dbatest>flashbacktable TEST_BAK to before drop ;

　　Flashback complete.

　　Elapsed: 00:00:00.02

　　YXYUP@dbatest>select* from tab;

　　TNAME TABTYPE CLUSTERID

　　TEST_BAK TABLE

　　TEST01 TABLE

　　Elapsed: 00:00:00.01

　　通过上面测试可以看出.

　　当recyclebin中有多个被删除的同时,并在表空间不足以放下要创建的新对象时,Oracle会FIFO的方式从回收站中自动彻底删除.