从Oracle 11G开始，数据库统计信息的自动收集被整合到自动维护任务中，满足大多数情形下的运行需求。但对于在线商城，交易系统而言，可能需要调整其执行时间或者自行指定收集窗口。本文描述了如何查看以及调整自动收集统计时间窗口等，供大家参考。
一、缺省的统计信息相关状态查看
1、查看自动收集统计信息对应的task(也就是program的名称)及状态
--当前状态
SQL> select * from v$version where rownum<2;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
--如下查询表明统计信息的收集是位于gather_stats_prog这个task，当前状态为enabled，即启用
SELECT client_name,task_name, status
FROM dba_autotask_task
WHERE client_name = 'auto optimizer stats collection';
CLIENT_NAME TASK_NAME STATUS
----------------------------------- ---------------------- --------
auto optimizer stats collection gather_stats_prog ENABLED
--下面查询dba_scheduler_programs
--在scheduler_programs中，程序GATHER_STATS_PROG调用
--dbms_stats.gather_database_stats_job_proc来实现统计信息的自动收集，如下查询
SQL> SELECT program_action, number_of_arguments, enabled
2 FROM dba_scheduler_programs
3 WHERE owner = 'SYS'
4 AND program_name = 'GATHER_STATS_PROG';
PROGRAM_ACTION NUMBER_OF_ARGUMENTS ENABL
------------------------------------------ ------------------- -----
dbms_stats.gather_database_stats_job_proc 0 TRUE
2、查看自动收集统计信息是否开启
SELECT CLIENT_NAME,
STATUS
FROM DBA_AUTOTASK_CLIENT
WHERE CLIENT_NAME = 'auto optimizer stats collection';
CLIENT_NAME STATUS
----------------------------------- --------
auto optimizer stats collection ENABLED
3、统计信息收集的窗口组，如下查询
SQL> SELECT window_group
2 FROM dba_autotask_client
3 WHERE client_name = 'auto optimizer stats collection';
WINDOW_GROUP
----------------------------------------------------------------
ORA$AT_WGRP_OS
4、查询统计信息收集的具体窗口
--统计信息收集的时间窗口
--如下查询周一至周五时间为22点，周六日为6点
--此外持续也不相同，周一至周五为4小时，周六日为20个小时
--enabled为true表明当前的这些作业处于激活状态
SELECT w.window_name,
w.repeat_interval,
w.duration,
w.enabled
FROM dba_autotask_window_clients c, dba_scheduler_windows w
WHERE c.window_name = w.window_name AND c.optimizer_stats = 'ENABLED';
WINDOW_NAME REPEAT_INTERVAL DURATION ENABL
------------------------- ------------------------------ ------------------------- -----
MONDAY_WINDOW freq=daily;byday=MON;byhour=22 +000 04:00:00 TRUE
;byminute=0; bysecond=0
TUESDAY_WINDOW freq=daily;byday=TUE;byhour=22 +000 04:00:00 TRUE
;byminute=0; bysecond=0
WEDNESDAY_WINDOW freq=daily;byday=WED;byhour=22 +000 04:00:00 TRUE
;byminute=0; bysecond=0
THURSDAY_WINDOW freq=daily;byday=THU;byhour=22 +000 04:00:00 TRUE
;byminute=0; bysecond=0
FRIDAY_WINDOW freq=daily;byday=FRI;byhour=22 +000 04:00:00 TRUE
;byminute=0; bysecond=0
SATURDAY_WINDOW freq=daily;byday=SAT;byhour=6; +000 20:00:00 TRUE
byminute=0; bysecond=0
SUNDAY_WINDOW freq=daily;byday=SUN;byhour=6; +000 20:00:00 TRUE
byminute=0; bysecond=0
4、查看自动收集统计信息历史执行情况
SELECT * --Author : Leshami
FROM dba_autotask_client_history --Blog : http://blog.csdn.net/leshami
WHERE client_name LIKE '%stats%';二、统计信息收集调度时间禁用及修改
1、启用自动收集统计信息
BEGIN
DBMS_AUTO_TASK_ADMIN.ENABLE (
client_name => 'auto optimizer stats collection',
operation => NULL,
window_name => NULL);
END;
2、禁用自动收集统计信息
BEGIN
DBMS_AUTO_TASK_ADMIN.DISABLE (
client_name => 'auto optimizer stats collection',
operation => NULL,
window_name => NULL);
END;
--执行上面的代码后，验证是否被禁用
SELECT CLIENT_NAME,
STATUS
FROM DBA_AUTOTASK_CLIENT
WHERE CLIENT_NAME = 'auto optimizer stats collection';
CLIENT_NAME STATUS
----------------------------------- --------
auto optimizer stats collection DISABLED
3、关闭单个调度时间窗口
BEGIN
DBMS_AUTO_TASK_ADMIN.disable (
client_name => 'auto optimizer stats collection',
operation => NULL,
window_name => 'MONDAY_WINDOW');
END;
/
--验证关闭情况，如下，optimizer_stats列为DISABLED
SQL> SELECT window_name,
2 window_next_time,
3 window_active,
4 optimizer_stats
5 FROM dba_autotask_window_clients
6 WHERE window_name = 'MONDAY_WINDOW'
7 ORDER BY window_next_time;
WINDOW_NAME WINDOW_NEXT_TIME WINDO OPTIMIZE
------------------------- ------------------------------------ ----- --------
MONDAY_WINDOW 27-MAR-17 10.00.00.000000 PM PRC FALSE DISABLED
4、关闭所有时间调度窗口，验证略
BEGIN
DBMS_AUTO_TASK_ADMIN.disable (
client_name => 'auto optimizer stats collection',
operation => NULL,
window_name => NULL);
END;
/
5、开启单个调度时间窗口及所有时间调度窗口，只需要使用enable过程
-- 注：单个应指定窗口名字，如window_name => 'MONDAY_WINDOW'
BEGIN
DBMS_AUTO_TASK_ADMIN.enable (
client_name => 'auto optimizer stats collection',
operation => NULL,
window_name => NULL);
END;
/
6、修改时间窗口到特定的时间
--如下示例，将周五时间窗口时间到晚间23点30分
BEGIN
DBMS_SCHEDULER.DISABLE (name => '"SYS"."FRIDAY_WINDOW"', force => TRUE);
END;
BEGIN
DBMS_SCHEDULER.SET_ATTRIBUTE (
name => '"SYS"."FRIDAY_WINDOW"',
attribute => 'REPEAT_INTERVAL',
VALUE => 'FREQ=WEEKLY;BYDAY=FRI;BYHOUR=23;BYMINUTE=30;BYSECOND=0');
END;
BEGIN
DBMS_SCHEDULER.ENABLE (name => '"SYS"."FRIDAY_WINDOW"');
END;
--验证修改
SELECT w.window_name,
w.repeat_interval,
w.duration,
w.enabled
FROM dba_autotask_window_clients c, dba_scheduler_windows w
WHERE c.window_name = w.window_name
AND c.optimizer_stats = 'ENABLED'
AND c.window_name = 'FRIDAY_WINDOW';
WINDOW_NAME REPEAT_INTERVAL DURATION ENABL
--------------- ------------------------------------------------------------ ------------ --------
FRIDAY_WINDOW FREQ=WEEKLY;BYDAY=FRI;BYHOUR=23;BYMINUTE=30;BYSECOND=0 +000 04:00:0 TRUE
7、新增维护时间窗口
-- 假定我们要处理的是修改周一的时间窗口
-- 首先关闭周一的时间窗口
BEGIN
DBMS_AUTO_TASK_ADMIN.disable (
client_name => 'auto optimizer stats collection',
operation => NULL,
window_name => 'MONDAY_WINDOW');
END;
/
--接下来创建一个窗口并设定时间调度间隔
--如下，每周一5点执行，持续时间为1小时
BEGIN
DBMS_SCHEDULER.create_window (
window_name => 'STATS_WINDOW',
resource_plan => 'DEFAULT_MAINTENANCE_PLAN',
repeat_interval => 'freq=daily;byday=MON;byhour=5;byminute=0; bysecond=0',
duration => INTERVAL '1' HOUR,
comments => 'Test window for stats task');
EXCEPTION
WHEN OTHERS
THEN
IF SQLCODE = -27477
THEN
NULL;
ELSE
RAISE;
END IF;
END;
BEGIN
DBMS_SCHEDULER.set_attribute ('STATS_WINDOW', 'SYSTEM', TRUE);
DBMS_SCHEDULER.set_attribute ('STATS_WINDOW',
'FOLLOW_DEFAULT_TIMEZONE',
TRUE);
EXCEPTION
WHEN OTHERS
THEN
IF SQLCODE = -27477
THEN
NULL;
ELSE
RAISE;
END IF;
END;
/
SQL> SELECT window_name, repeat_interval, enabled
2 FROM dba_scheduler_windows
3 WHERE window_name = 'STATS_WINDOW';
WINDOW_NAME REPEAT_INTERVAL ENABL
------------------------------ ------------------------------------------------------------ -----
STATS_WINDOW freq=daily;byday=MON;byhour=5;byminute=0; bysecond=0 TRUE
--接下来将窗口STATS_WINDOW添加到维护窗口组
BEGIN
DBMS_SCHEDULER.add_window_group_member ('MAINTENANCE_WINDOW_GROUP',
'STATS_WINDOW');
END;
/
SQL> SELECT WINDOW_NAME,
2 WINDOW_NEXT_TIME,
3 WINDOW_ACTIVE,
4 OPTIMIZER_STATS
5 FROM DBA_AUTOTASK_WINDOW_CLIENTS
6 WHERE WINDOW_NAME in ('STATS_WINDOW','MONDAY_WINDOW')
7 ORDER BY WINDOW_NEXT_TIME;
WINDOW_NAME WINDOW_NEXT_TIME WINDO OPTIMIZE
------------------------------ -------------------------------------- ----- --------
STATS_WINDOW 27-MAR-17 05.00.00.000000 AM PRC FALSE ENABLED --允许
MONDAY_WINDOW 27-MAR-17 10.00.00.000000 PM PRC FALSE DISABLED --当前被disabled三、手工执行统计信息的自动收集
SQL> create table scott.tb_objs as select * from dba_objects;
SQL> select TABLE_NAME,NUM_ROWS,BLOCKS,LAST_ANALYZED from dba_tables where TABLE_NAME='TB_OBJS';
TABLE_NAME NUM_ROWS BLOCKS LAST_ANAL
------------------------------ ---------- ---------- ---------
TB_OBJS
--执行下面的这个存储过程
SQL> EXEC DBMS_AUTO_TASK_IMMEDIATE.GATHER_OPTIMIZER_STATS;
PL/SQL procedure successfully completed.
--如下查询，scott表上的统计信息已更新
SQL> select TABLE_NAME,NUM_ROWS,BLOCKS,LAST_ANALYZED from dba_tables where TABLE_NAME='TB_OBJS';
TABLE_NAME NUM_ROWS BLOCKS LAST_ANAL
------------------------------ ---------- ---------- ---------
TB_OBJS 75548 1103 25-MAR-17四、参考链接
How to use an own Maintenance Window for the Statistics Collection in 11g [ID 1300313.1]
MOS相关文档： FAQ: Automatic Statistics Collection [ID 1233203.1]
[dbms_stats 导入导出 schema 级别统计信息](http://blog.csdn.net/leshami/article/details/8938201)
