SQL> select addr,used_ublk from v$transaction;
?
no rows selected

SQL> select begin_time,end_time,undoblks from v$undostat;
?
BEGIN_TIM END_TIME??? UNDOBLKS
--------- --------- ----------
19-SEP-11 19-SEP-11????????? 0
19-SEP-11 19-SEP-11???????? 80
19-SEP-11 19-SEP-11???????? 16

以 houzh/houzh登录
向t表中插入10000条记录，不提交
SQL> begin
? 2? for i in 1 .. 10000
? 3? loop
? 4?? insert into t values(i,'houzhh');
? 5? end loop;
? 6? end;
? 7? /
?
PL/SQL procedure successfully completed.
插入100W条数据时查看有多少undo blocks 使用

start_time --> start_time
start_scnb --> 开始的scn

used_urec --> undo 记录的行数

used_ublk --> 占用的undo block

SQL> select addr, START_TIME,START_SCNB,used_ublk,used_urec from v$transaction;
?
ADDR???? START_TIME?????????? START_SCNB? USED_UBLK? USED_UREC
-------- -------------------- ---------- ---------- ----------
37F6072C 09/19/11 20:57:20?????? 1328853???????? 88????? 10000

?

在另一个客户端同样以houzh/houzh登录

插入

SQL> begin
? 2? for i in 10000 .. 100000
? 3? loop
? 4?? insert into t values(i,'houzhh');
? 5? end loop;
? 6? end;
? 7? /
?
PL/SQL procedure successfully completed.

SQL> select addr, START_TIME,START_SCNB,used_ublk,used_urec from v$transaction;
?
ADDR???? START_TIME?????????? START_SCNB? USED_UBLK? USED_UREC
-------- -------------------- ---------- ---------- ----------
37F6072C 09/19/11 20:57:20?????? 1328853???????? 88????? 10000
37F7C0D0 09/19/11 20:59:32?????? 1328933??????? 777????? 90001

SQL> select begin_time,end_time,undoblks from v$undostat;
?
BEGIN_TIM END_TIME??? UNDOBLKS
--------- --------- ----------
19-SEP-11 19-SEP-11????? 10223
19-SEP-11 19-SEP-11???????? 80
19-SEP-11 19-SEP-11???????? 16
SQL> commit;
?
Commit complete.
?
SQL> select addr,used_ublk from v$transaction;
?
no rows selected