ORA-01555 When Max Query Length Is Less Than Undo Retention, small or 0 Seconds (Doc ID 1131474.1)(示

Posted 2020-11-23 zylong-sys

ORA-01555 When Max Query Length Is Less Than Undo Retention, small or 0 Seconds (Doc ID 1131474.1)

APPLIES TO:

Oracle Database - Enterprise Edition - Version 10.2.0.1 to 11.2.0.2 [Release 10.2 to 11.2]
Oracle Database - Enterprise Edition - Version 11.2.0.3 to 11.2.0.4 [Release 11.2]
Oracle Database - Enterprise Edition - Version 12.1.0.2 to 12.1.0.2 [Release 12.1]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Information in this document applies to any platform.

SYMPTOMS

Symptoms:
- A job or process is consistently giving ORA-1555 errors. 

-  job or process持续出现ORA-1555错误

- Increasing the undo_retention value has not stopped the errors.

- 增加undo_retention值并未停止错误

- The ORA-1555 occurs even if there are no other jobs/processes updating the objects reported in the failed SQL.

- 即使没有其他 jobs/processes 更新失败SQL中报告的对象，也会发生ORA-1555

- The datafiles for the undo tablespace have autoextend turned on, and the file size is less than MAXBYTES.

- undo tablespace的数据文件已启用自动扩展，并且文件大小小于MAXBYTES

- A look at the v$undostat shows that the query length is less than both the undo_retention and the tuned_undoretention

- 查看 v$undostat 显示查询长度小于undo_retention和tuned_undoretention两者

To find the max query length and the tuned_undo retention, run this SQL.
--要查找最大查询长度和tuned_undo retention，请运行此SQL

set pagesize 25
set linesize 100
column UNXPSTEALCNT heading "# Unexpired|Stolen"
column EXPSTEALCNT heading "# Expired|Reused"
column SSOLDERRCNT heading "ORA-1555|Error"
column NOSPACEERRCNT heading "Out-Of-space|Error"
column MAXQUERYLEN heading "Max Query|Length"
select inst_id, to_char(begin_time,‘MM/DD/YYYY HH24:MI‘) begin_time,
UNXPSTEALCNT, EXPSTEALCNT , SSOLDERRCNT, NOSPACEERRCNT, MAXQUERYLEN, TUNED_UNDORETENTION
from gv$undostat
order by inst_id, begin_time;

Then look for the timestamp at which the ORA-1555 occurred.
--然后查找发生ORA-1555的时间戳
The max query length will be less than undo_retention, and less than tuned_undoretention.
--max query length 将小于 undo_retention，并且小于tuned_undoretention
Note: When tuned_undoretention is used, the undo_retention becomes a minimum setting.
--注意：使用tuned_undoretention时，undo_retention成为最小设置。

Here is an example of the output of the above SQL  这是上述SQL输出的示例

                      Unexpired  Expired ORA-1555 Out-Of-space  Max Query
INST_ID BEGIN_TIME     Stolen     Reused    Error        Error     Length TUNED_UNDORETENTION
------- ---------------- ----     ------    ----- ------------ ---------- ------------
1       06/14/2010 20:51    0          0        0            0        719     2000
1       06/14/2010 21:01    0          0        1            0       1323     2225 <--ORA-1555 here
1       06/14/2010 21:11    0          0        0            0        699     2000
1       06/14/2010 21:21    0          0        0            0       1303     2205
1       06/14/2010 21:31    0          0        0            0        678     2000

 

We can see that there were no stolen unexpired extents, and the length of the query was 1323 seconds, while the tuned_undoretention was 2225 seconds.

我们可以看到没有未到期的扩展数据段，查询的长度为1323秒，而tuned_undoretention为2225秒。

There were also no out-of-space errors.  也没有空间不足的错误

CAUSE

The issue can be caused by two reasons:  该问题可能是由于两个原因引起的

1. Indexes/table mismatch  索引/表不匹配

OR

2. Similar issue is reported as Bug 8231583 Abstract: ORA-1555 WHEN QUERY LENGTH < TUNED RETENTION

2. 相似的问题报告为 Bug 8231583 Abstract: ORA-1555 WHEN QUERY LENGTH < TUNED RETENTION

The bug has been closed at this point without finding a root issue.  The problem is not easy to reproduce consistently.

该错误目前已关闭，没有找到根本问题。问题不容易一致地重现。

SOLUTION

1. If the 1555 error is consistently reported against a certain table each time, so this most like is caused by Indexes/table mismatch and you need to drop/recreate (not rebuild) all table indexes.

1. 如果每次都针对某个表始终报告1555错误，那么这很像是由 Indexes/table 不匹配引起的，您需要 drop/recreate (not rebuild) 所有表索引

Similar issue described in Note: 977902.1.

2. Bug 8231583 reported on this issue is closed due to the lack of reproducibility.

2. 由于缺乏可重复性，因此已报告关于此问题的错误8231583

There are a few workarounds identified for this issue. One option is to create a new undo tablespace and switch to the new Undo tablespace.

有一些解决此问题的方法。一种选择是创建一个新的undo tablespace并切换到新的Undo tablespace

For example:

CREATE UNDO TABLESPACE undotbs_02
DATAFILE ‘/u01/oracle/rbdb1/undo0201.dbf‘ SIZE 2M REUSE AUTOEXTEND ON;

ALTER SYSTEM SET UNDO_TABLESPACE = undotbs_02;

The old undo can only be dropped after all transactions have cleared from the undo tablespace.

只有在undo tablespace中清除了所有事务之后，才能删除旧的undo 

Please refer to the Oracle Database Administrator‘s manual for creating a new undo, switching to a new undo tablespace, and dropping the undo tablespace.

请参考Oracle数据库管理员手册，以创建新的undo，切换到新的undo tablespace并删除undo tablespace

Oracle Database Administrator‘s Guide
10g Release 2 (10.2)
Chapter 10 Managing the Undo Tablespace

Oracle Database Administrator‘s Guide
11g Release 2 (11.2)
Chapter 15 Managing Undo
Section: Managing Undo Tablespaces

As a second option, disable auto tuning by setting  第二种选择是通过设置disable auto tuning

"_undo_autotune" = false

after creating a new undo tablespace has avoided future occurrences of the problem condition at some database locations. 

创建新的undo tablespace后，避免了将来在某些数据库位置出现问题情况。

Until a consistent, reproducible test case can be developed in-house this problem remains unresolved.

在内部开发出一致，可重复的测试用例之前，这个问题仍然没有解决。

3. Afterwords, If this is still consistently reproducible in your database then to progress this with development, check Note: 761128.1 to get diagnostic information needs to be collected at the time the ORA-01555 error occurs to be able to engage development.
3. 后记，如果仍然可以在您的数据库中始终复制此代码，则要继续进行开发，请检查注：761128.1以获取诊断信息，以便在发生ORA-01555错误时能够进行开发。

REFERENCES

NOTE:461480.1 - FAQ – Automatic Undo Management (AUM) / System Managed Undo (SMU)
NOTE:877613.1 - AUM Common Analysis/Diagnostic Scripts
BUG:18602141 - ORA-1555 QUERY FAILING BEFORE UNDO_RETENTION IS REACHED
BUG:19014280 - ACTIVE DG: LGWR BLOCKS SEVERAL SESSIONS DURING GLOBAL FLUSH
BUG:18899974 - ORA-600 [KCBGTCR_13] ON ACTIVE DATAGUARD
BUG:8231583 - ORA-01555 WHEN QUERY LENGTH < TUNED RETENTION
BUG:8231583 - ORA-01555 WHEN QUERY LENGTH < TUNED RETENTION
NOTE:240746.1 - 10g NEW FEATURE on AUTOMATIC UNDO RETENTION