环境：Oracle 11.2.0.3 RAC
问题：统计信息自动收集任务失效原因排查
- 1.查看自动任务的状态
- 2.进一步查看其它信息
- 3.解决问题
1.查看自动任务的状态
查看自动任务的状态，确认是enabled状态：
SQL> select client_name,status from dba_autotask_client;
CLIENT_NAME STATUS
---------------------------------------------------------------- --------
auto optimizer stats collection ENABLED
auto space advisor ENABLED
sql tuning advisor ENABLED
Elapsed: 00:01:03.88一般来说，这样的结果，就意味着统计信息自动收集是打开的，如今却是没有自动收集。说明确实是有故障，需要进一步深入排查。
若对这些自动任务的状态不理解可以参考之前文章：
- Oracle的窗口和自动任务
2.进一步查看其它信息
根据 Why Auto Optimizer Statistics Collection May Appear to be "Stuck" and Not Running? (文档 ID 1320246.1)
排查以下项：
The 'auto optimizer stats collection' task is enabled in auto task
STATISTICS_LEVEL has already been set to TYPICAL or FULL
dba_autotask_client_history is empty
Statistics on tables are stale.
Some scheduler window is active and LAST_START_DATE is several days ago.
具体操作记录如下：
--STATISTICS_LEVEL：
SQL> show parameter STATISTICS_LEVEL
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
statistics_level string TYPICAL
--dba_autotask_client_history is empty：
SQL> select * from dba_autotask_client_history;
no rows selected
Elapsed: 00:01:04.79
--Some scheduler window is active and LAST_START_DATE 是20-SEP-12 10.00.00.010777 PM
SELECT window_name, last_start_date, enabled, active FROM dba_scheduler_windows;
SQL> SELECT window_name ,
2 last_start_date,
3 enabled ,
4 active
5 FROM dba_scheduler_windows;
WINDOW_NAME LAST_START_DATE ENABL ACTIV
------------------------------ --------------------------------------------------------------------------- ----- -----
MONDAY_WINDOW 22-JAN-18 10.00.00.014299 PM PRC TRUE FALSE
TUESDAY_WINDOW 23-JAN-18 10.00.01.076798 PM PRC TRUE FALSE
WEDNESDAY_WINDOW 24-JAN-18 10.00.00.055066 PM PRC TRUE FALSE
THURSDAY_WINDOW 20-SEP-12 10.00.00.010777 PM PRC TRUE TRUE
FRIDAY_WINDOW 26-JAN-18 10.00.00.725176 PM PRC TRUE FALSE
SATURDAY_WINDOW 27-JAN-18 06.00.00.010751 AM PRC TRUE FALSE
SUNDAY_WINDOW 28-JAN-18 06.00.00.593207 AM PRC TRUE FALSE
WEEKNIGHT_WINDOW FALSE FALSE
WEEKEND_WINDOW FALSE FALSE
9 rows selected.
Elapsed: 00:00:00.01可以看到，如今的环境确实完全匹配文档列出的这些特征项。
另外，看下统计信息自动收集任务的WINDOW_GROUP以及对应的MEMBER_NAME：
SQL> select client_name,window_group
2 from DBA_AUTOTASK_CLIENT
3 where client_name = 'auto optimizer stats collection';
CLIENT_NAME WINDOW_GROUP
---------------------------------------------------------------- ----------------------------------------------------------------
auto optimizer stats collection ORA$AT_WGRP_OS
Elapsed: 00:01:05.39
SQL> SELECT * FROM dba_scheduler_group_members
2 where group_name='ORA$AT_WGRP_OS';
OWNER GROUP_NAME MEMBER_NAME
------------------------------ ------------------------------ -----------------------------------------------------------------------------------------------------------------------------------
SYS ORA$AT_WGRP_OS "SYS"."MONDAY_WINDOW"
SYS ORA$AT_WGRP_OS "SYS"."TUESDAY_WINDOW"
SYS ORA$AT_WGRP_OS "SYS"."WEDNESDAY_WINDOW"
SYS ORA$AT_WGRP_OS "SYS"."THURSDAY_WINDOW"
SYS ORA$AT_WGRP_OS "SYS"."FRIDAY_WINDOW"
SYS ORA$AT_WGRP_OS "SYS"."SATURDAY_WINDOW"
SYS ORA$AT_WGRP_OS "SYS"."SUNDAY_WINDOW"
7 rows selected.
Elapsed: 00:00:00.04可以看到，正常应该是一周7天都有的，但是由于THURSDAY_WINDOW 的窗口ACTIVE是TRUE，导致2012年9月27号（周四）统计信息收集失败。根据MOS描述，会影响其后的窗口都打开失败，进而导致之后所有自动任务的执行都失败。
我实际在我的测试环境验证也是如此，现象如下：
SQL> SELECT window_name, last_start_date, enabled, active FROM dba_scheduler_windows;
WINDOW_NAME LAST_START_DATE ENABLED ACTIVE
------------------------------------------------------------ --------------------------------------------------------------------------- ---------- ----------
MONDAY_WINDOW 22-JAN-18 10.00.00.011111 PM EST5EDT TRUE FALSE
TUESDAY_WINDOW 23-JAN-18 10.22.54.068776 PM EST5EDT TRUE FALSE
WEDNESDAY_WINDOW 24-JAN-18 10.00.00.005654 PM EST5EDT TRUE FALSE
THURSDAY_WINDOW 25-JAN-18 10.00.00.009885 PM EST5EDT TRUE FALSE
FRIDAY_WINDOW 26-JAN-18 10.00.00.010077 PM EST5EDT TRUE FALSE
SATURDAY_WINDOW 27-JAN-18 05.00.00.004156 PM EST5EDT TRUE FALSE
SUNDAY_WINDOW 28-JAN-18 01.00.00.010044 PM EST5EDT TRUE TRUE
WEEKNIGHT_WINDOW FALSE FALSE
WEEKEND_WINDOW FALSE FALSE
9 rows selected.
SQL> EXECUTE DBMS_SCHEDULER.OPEN_WINDOW ('MONDAY_WINDOW','');
BEGIN DBMS_SCHEDULER.OPEN_WINDOW ('MONDAY_WINDOW',''); END;
*
ERROR at line 1:
ORA-27480: window "SUNDAY_WINDOW" is currently open
ORA-06512: at "SYS.DBMS_ISCHED", line 493
ORA-06512: at "SYS.DBMS_SCHEDULER", line 1220
ORA-06512: at line 1
SQL> 可以看到我测试环境，因为周日的窗口已经是ACTIVE，再尝试打开周一的窗口就会报错，看起来同时就只能有一个窗口ACTIVE，这与MOS的描述也完全一致。
3.解决问题
根据MOS解决建议手工关闭活动的窗口，我这里就是关闭THURSDAY_WINDOW窗口：
SQL> EXECUTE DBMS_SCHEDULER.CLOSE_WINDOW ('THURSDAY_WINDOW');
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.14再次查询状态，确认窗口状态已关闭：
SQL> SELECT window_name ,
2 last_start_date,
3 enabled ,
4 active
5 FROM dba_scheduler_windows;
WINDOW_NAME LAST_START_DATE ENABL ACTIV
------------------------------ --------------------------------------------------------------------------- ----- -----
MONDAY_WINDOW 22-JAN-18 10.00.00.014299 PM PRC TRUE FALSE
TUESDAY_WINDOW 23-JAN-18 10.00.01.076798 PM PRC TRUE FALSE
WEDNESDAY_WINDOW 24-JAN-18 10.00.00.055066 PM PRC TRUE FALSE
THURSDAY_WINDOW 20-SEP-12 10.00.00.010777 PM PRC TRUE FALSE
FRIDAY_WINDOW 26-JAN-18 10.00.00.725176 PM PRC TRUE FALSE
SATURDAY_WINDOW 27-JAN-18 06.00.00.010751 AM PRC TRUE FALSE
SUNDAY_WINDOW 28-JAN-18 06.00.00.593207 AM PRC TRUE FALSE
WEEKNIGHT_WINDOW FALSE FALSE
WEEKEND_WINDOW FALSE FALSE
9 rows selected.这样就找到了问题，另外因为离统计信息信息自动收集关闭已有多年，目前生产环境运行平稳，所以最终决定保守处理，即：先将生产环境的自动任务都关闭，等在备库测试验证后再考虑生产环境开启自动任务。
Reference
- Why Auto Optimizer Statistics Collection May Appear to be "Stuck" and Not Running? (文档 ID 1320246.1)