v$session_event中的SID与v$session不一致的BUG

王朝other·作者佚名 2006-01-09

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总述：Oracle 9.2.0.1在察看会话等待事件时显示错位。TOAD等工具也没有修正这一错误，会造成通过session browser察看会话时看到的等待事件及合计实际是其他会话的。

问题的本质是Oracle 9.2.0.1的v$session_event视图中的SID与v$session中的SID相差了1。这一bug在9.2.0.3后修复。在没有升级的情况下可以使用如下语句察看会话的等待事件累计：

select b.sid,

decode(b.username, null, substr(b.program, 18), b.username) username,event,

a.total_waits,

a.total_timeouts,

a.time_waited,

a.average_wait,

a.max_wait,

a.time_waited_micro

from v$session_event a, v$session b

where b.sid = a.sid + 1

order by b.sid, a.time_waited desc

原BUG说明如下：

Bug 号 2429929

已归档 24-JUN-2002 已更新 02-SEP-2003

产品 Oracle Server - Enterprise Edition 产品版本 9.2.0.1.0

平台 HP Tru64 UNIX 平台版本 5.1

数据库版本 9.2.0.1.0 影响平台 Generic

优先级 Severe Loss of Service 状态 Development to Q/A

基本 Bug N/A 修复产品版本 10I

问题陈述:

SID VALUES IN V$SESSION AND V$SESSION_EVENTS DOES NOT MATCH

*** 06/24/02 04:17 am ***

TAR:

----

SMS-TAR DE:2428765.999

PROBLEM:

--------

The SID value in V$SESSION_EVENT is appearing to be one number less than in

V$SESSION

Example:

SQL> SELECT DISTINCT SID FROM V$SESSION;

SID

----------

12 rows selected

SQL> SELECT DISTINCT SID FROM V$SESSION_EVENT;

SID

----------

12 < < <

31 < < < SID's 12 & 31 doesn't exists in v$session

11 rows selected

DIAGNOSTIC ANALYSIS:

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

v$fixed_view_definition shows there is no change in view definition for

gv$session_event in 9.2 as compared to earlier releases like 9.0.1 and 8.x

WORKAROUND:

-----------

None

RELATED BUGS:

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

None

REPRODUCIBILITY:

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

YES

TEST CASE:

----------

SQL> SELECT DISTINCT SID FROM V$SESSION;

SQL> SELECT DISTINCT SID FROM V$SESSION_EVENT;

compare both the output

STACK TRACE:

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

None

SUPPORTING INFORMATION:

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

24 HOUR CONTACT INFORMATION FOR P1 BUGS:

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

DIAL-IN INFORMATION:

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

IMPACT DATE:

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

Cannot upgrade production db to 9.2 unless this is fixed, since all

performance

diagnostic tools are affected

*** 06/24/02 10:01 pm *** (CHG: Sta->16 Asg->NEW OWNER)

*** 06/24/02 11:26 pm ***

*** 06/24/02 11:47 pm ***

*** 06/24/02 11:48 pm ***

*** 06/24/02 11:49 pm *** (CHG: Sta->11 Asg->NEW OWNER)

*** 06/25/02 06:43 pm *** (CHG: Asg->NEW OWNER)

*** 06/25/02 06:43 pm ***

*** 07/19/02 02:57 pm *** (CHG: Asg->NEW OWNER)

*** 07/19/02 02:57 pm ***

SHould be looked at by the VOS owner first

*** 07/22/02 02:19 am *** (CHG: DevPri->2)

*** 07/23/02 07:19 am ***

*** 08/12/02 03:33 am ***

*** 08/19/02 02:41 am ***

*** 08/20/02 01:40 am ***

*** 08/21/02 02:20 am ***

*** 08/22/02 07:19 am *** (CHG: Sta->80)

*** 08/22/02 07:19 am *** (CHG: Confirmed Flag->Y)

*** 08/22/02 07:19 am *** (CHG: Fixed->10I)

*** 08/22/02 07:19 am ***

Rediscovery Information:

To be seeing this bug the following must be true :

1. You are on a release that is 9.2.0.1 or higher

2. V$SESSION_EVENTS will have a missing SID when compared to V$SESSION

3. The wait information is out of sequence. Session 2's waits will be

reported under session 1, session 3's waits under session 2 and so on

]] [G]V$SESSION_WAIT now returns the correct wait information for a specified

]] sessionid

*** 09/17/02 11:16 pm ***

*** 10/22/02 04:26 am ***

Backported to 9.2.0.1.99

*** 10/24/02 11:37 am ***

*** 10/25/02 07:00 am ***

*** 11/05/02 08:00 am ***

*** 11/07/02 11:29 am ***

*** 11/13/02 07:21 am ***

Backported to 9.2.0.3

*** 11/20/02 02:14 pm ***

*** 11/22/02 05:36 am ***

*** 11/26/02 07:20 am ***

*** 11/27/02 09:14 am ***

*** 01/17/03 05:39 am ***

*** 01/17/03 05:41 am ***

*** 02/26/03 11:41 am ***

*** 03/18/03 08:43 pm ***

*** 03/19/03 05:53 am ***

*** 03/28/03 12:37 pm ***

*** 03/28/03 01:26 pm ***

*** 03/28/03 05:29 pm ***

*** 04/28/03 08:20 pm ***

*** 04/28/03 08:22 pm ***

*** 07/18/03 10:14 am ***

*** 09/02/03 12:58 pm ***

Oracle网站对此问题给出了说明，并在9.2.0.3中修复：

文档 ID: 注释:208105.1

主题: ALERT: SID Values in V$SESSION and V$SESSION_EVENT Do Not Match

类型: ALERT

状态: PUBLISHED

内容类型: TEXT/PLAIN

创建日期: 22-AUG-2002

上次修订日期: 08-APR-2003

ALERT: SID Values in V$SESSION and V$SESSION_EVENT Do Not Match

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Versions Affected

~~~~~~~~~~~~~~~~~

This problem is introduced in Oracle Server 9.2.0.1 and is present in 9.2.0.2

An attempt is made here in this article to increase the visibility of

[BUG:2429929] which many customers are facing as they move on to Oracle9i

The fix to this bug is addressed in Oracle Server patchset 9.2.0.3 and above

Platforms Affected

~~~~~~~~~~~~~~~~~~

GENERIC

Description

~~~~~~~~~~~

The V$SESSION_EVENT and GV$SESSION_EVENT views in Oracle Server 9.2.0.1 and

9.2.0.2 will return misleading information as the SID column has incorrect

value (i.e., V$SESSION_EVENT.SID actually has value V$SESSION.SID - 1)

Hence, any joins between V$SESSION_EVENT and V$SESSION will return information

for the wrong session unless V$SESSION.SID - 1 is used in join predicate

This article is intended for customers who use Oracle's or third party

provided performance measurement and diagnostics Tools / Scripts / SQL's

This includes Oracle Enterprise Manager (OEM), UTLBSTAT-ESTAT, STATSPACK, etc

Likelihood of Occurrence

~~~~~~~~~~~~~~~~~~~~~~~~

Customers are very unlikely to be aware of this bug as there is no error

associated

Comparing the output for below two SQL's in Oracle Server 9.2.0.1 and 9.2.0.2

will reveal that the SID value in V$SESSION_EVENT is appearing to be one

number less than in V$SESSION

SQL> SELECT DISTINCT SID FROM V$SESSION

SQL> SELECT DISTINCT SID FROM V$SESSION_EVENT

Example:

SQL> SELECT DISTINCT SID FROM V$SESSION;

SID

----------

12 rows selected

SQL> SELECT DISTINCT SID FROM V$SESSION_EVENT;

SID

----------

12 <<<

31 <<< SID's 12 & 31 doesn't exists in v$session

11 rows selected

Possible Symptoms

~~~~~~~~~~~~~~~~~

Customers will receive conflicting results when performing a query like the one

below. This type of query is often run when trying to trace

sessions using a disproportionate amount of resources

Finding the SID/SERIAL# of a user showing a particular type of wait:

SELECT s.sid , s.serial#, s.status, s.server, s.username,

e.event, e.time_waited

FROM v$session_event e, v$session s

WHERE e.sid=s.sid

AND e.event like '&WAITEVENT_TO_CHECK'

AND e.time_waited > '&WAIT_TIME_THRESHOLD'

Workaround

~~~~~~~~~~

Use join predicate V$SESSION_EVENT.SID = V$SESSION.SID - 1 in SQL queries

Patches

~~~~~~~

Fix to this bug is addressed in Oracle Server patchset 9.2.0.3 and above

In order to ensure the highest level of support, Oracle strongly recommends

you to apply the latest patchset available for your platform

References

~~~~~~~~~~

[BUG:2429929] SID VALUES IN V$SESSION AND V$SESSION_EVENT DOES NOT MATCH

Rediscovery Information

~~~~~~~~~~~~~~~~~~~~~~~

To be seeing this bug the following must be true:

1. You are on a release that is 9.2.0.1 or 9.2.0.2

2. V$SESSION_EVENT will have a missing SID when compared to V$SESSION

3. The wait information is out of sequence. Session 2's waits will be

reported under session 1, session 3's waits under session 2 and so on.