Oracle自动维护任务

最近看到alter日志里面有VKRM的报错信息，所以查询学习了下。
 
From Oracle 11g, each day has its own windows and each of it has been specified default resource plan.This is something new for me too.So, i think that would be reason for seeing VKRM process in the alert log.
 
 
 
SQL> select WINDOW_NAME,RESOURCE_PLAN from DBA_SCHEDULER_WINDOWS;
 
 
 
WINDOW_NAME                    RESOURCE_PLAN
 
------------------------------ ------------------------------
 
MONDAY_WINDOW                  DEFAULT_MAINTENANCE_PLAN
 
TUESDAY_WINDOW                DEFAULT_MAINTENANCE_PLAN
 
WEDNESDAY_WINDOW              DEFAULT_MAINTENANCE_PLAN
 
THURSDAY_WINDOW                DEFAULT_MAINTENANCE_PLAN
 
FRIDAY_WINDOW                  DEFAULT_MAINTENANCE_PLAN
 
SATURDAY_WINDOW                DEFAULT_MAINTENANCE_PLAN
 
SUNDAY_WINDOW                  DEFAULT_MAINTENANCE_PLAN
 
WEEKNIGHT_WINDOW
 
WEEKEND_WINDOW
 
 
 
SYS@>AppD> SELECT WINDOW_GROUP_NAME,ENABLED,NEXT_START_DATE,COMMENTS FROM DBA_SCHEDULER_WINDOW_GROUPS
 
 
 
WINDOW_GROUP_NAME              ENABL NEXT_START_DATE                          COMMENTS
 
-------------------------- ----------------------------------------  --------------------------------------
 
MAINTENANCE_WINDOW_GROUP      TRUE  14-MAR-11 10.00.00.000000 PM  Window group for Automated Maintenance
 
ORA$AT_WGRP_OS                TRUE  14-MAR-11 10.00.00.000000 PM  auto optimizer stats collection
 
ORA$AT_WGRP_SA                TRUE  14-MAR-11 10.00.00.000000 PM  auto space advisor
 
ORA$AT_WGRP_SQ                TRUE  14-MAR-11 10.00.00.000000 PM  sql tuning advisor
 
 
 
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
 
 
 
自动维护任务是一种按规则自动启动的数据库维护操作任务。比如自动收集为查询优化器使用的统计信息。自动维护任务按维护窗口自动运行。所谓自动维护窗口是按照预定义的间隔时间窗口。