分析表- 自动搜集统计信息-索引使用情况
分区表推荐用: EXEC dbms_stats.gather_table_stats(ownname => 'SCHEMA', tabname => 'TABLE_NAME', cascade => TRUE, degree => number of cpu, estimate_percent => 100); 一般的表(tom高效设计中的方法): analyze table table_name compute statistics for table for all indexes for all indexed columns;
修改11g 自动收集统计信息的执行时间2012-11-12 21:01:04
分类: Oracle
oracle 11g自动收集统计信息的时间是22:00--2:00 这个时段往往是业务的高峰期,给本已紧张的系统带来更大的负担。所以,应该把自动执行的时间改到空闲的时段。
--获得当前自动收集统计信息的执行时间
select t1.window_name,t1.repeat_interval,t1.duration from dba_scheduler_windows t1,dba_scheduler_wingroup_members t2
where t1.window_name=t2.window_name and t2.window_group_name in ('MAINTENANCE_WINDOW_GROUP','BSLN_MAINTAIN_STATS_SCHED');
WINDOW_NAME REPEAT_INTERVAL DURATION
------------------------------ ------------------------------------------------------------ ---------------------------------------------------------------------------
MONDAY_WINDOW freq=daily;byday=MON;byhour=22;byminute=0; bysecond=0 0 4:0:0.0
TUESDAY_WINDOW freq=daily;byday=TUE;byhour=22;byminute=0; bysecond=0 0 4:0:0.0
WEDNESDAY_WINDOW freq=daily;byday=WED;byhour=22;byminute=0; bysecond=0 0 4:0:0.0
THURSDAY_WINDOW freq=daily;byday=THU;byhour=22;byminute=0; bysecond=0 0 4:0:0.0
FRIDAY_WINDOW freq=daily;byday=FRI;byhour=22;byminute=0; bysecond=0 0 4:0:0.0
SATURDAY_WINDOW freq=daily;byday=SAT;byhour=6;byminute=0; bysecond=0 0 20:0:0.0
SUNDAY_WINDOW freq=daily;byday=SUN;byhour=6;byminute=0; bysecond=0 0 20:0:0.0
--WINDOW_NAME:任务名
--REPEAT_INTERVAL:任务重复间隔时间
--DURATION:持续时间
修改的步骤:
--1.停止任务
BEGIN
DBMS_SCHEDULER.DISABLE(
name=>'"SYS"."FRIDAY_WINDOW"',
force=>TRUE);
END;
--2.修改任务的持续时间,单位是分钟
BEGIN
DBMS_SCHEDULER.SET_ATTRIBUTE(
name=>'"SYS"."FRIDAY_WINDOW"',
attribute=>'DURATION',
value=>numtodsinterval(180, 'minute'));
END;
--3.开始执行时间,BYHOUR=2,表示2点开始执行
BEGIN
DBMS_SCHEDULER.SET_ATTRIBUTE(
name=>'"SYS"."FRIDAY_WINDOW"',
attribute=>'REPEAT_INTERVAL',
value=>'FREQ=WEEKLY;BYDAY=MON;BYHOUR=2;BYMINUTE=0;BYSECOND=0');
END;
--4.开启任务
BEGIN
DBMS_SCHEDULER.ENABLE(
name=>'"SYS"."FRIDAY_WINDOW"');
END; 1、查看自动收集统计信息的任务及状态 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
要看索引的使用情况,从9I之后可以用alter index indexname monitoring usage来实现: 监控使用情况: select 'alter index 'index_name' monitoring usage' from user_indexes; 停止监控: select 'alter index 'index_name' nomonitoring usage' from user_indexes; 未使用得到的索引: select index_name,table_name from v$object_usage where used='NO';
select 'alter index '||index_name||' monitoring usage'||';' from user_indexes; select 'alter index '||index_name||' nomonitoring usage'||';' from user_indexes; select * from v$sql_plan select * from v$object_usage where used<>'NO'