不知道这是什么意思?我刚刚试过,但是没有发现有什么功能!偶比较笨!
SQL> select * from a;DATEA
---------
02-FEB-00
01-FEB-01
01-JAN-02
02-FEB-03SQL> alter table a deallocate unused ;Table altered.SQL> commit;Commit complete.SQL> select * from a;DATEA
---------
02-FEB-00
01-FEB-01
01-JAN-02
02-FEB-03
SQL> select * from a;DATEA
---------
02-FEB-00
01-FEB-01
01-JAN-02
02-FEB-03SQL> alter table a deallocate unused ;Table altered.SQL> commit;Commit complete.SQL> select * from a;DATEA
---------
02-FEB-00
01-FEB-01
01-JAN-02
02-FEB-03
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2. begin
for i in 1..400 loop
insert into ta values ( 1, 1);
commit;
end loop;
end;3. select * from user_segments where segment_name = 'TA'
bytes blocks Extents
71680 35 4 4. delete from ta ;
commit;
select * from user_segments where segment_name = 'TA'
bytes blocks Extents
71680 35 4 --> the hwm is not reset 5. alter table ta deallocate unused
bytes blocks Extents
61440 30 4 To be very surprised , although I delete all the records then issue deallocate command , only 5 blocks space has been withdrawed . what happen to the left 30 blocks ? I guess it's a bug of oracle7.3 . ( To be frankly , I tried it on my personal oracle7.3 , I was wrong in my previous statement , it is not the new feature in oracle 8i , in fact , it is available since oracle 7.3 at least )