清理SYSAUX表空间的WRH$_LATCH_CHILDREN表

周六 被突然起来的短信 轰醒. 一看有63条短信. 都是来之与监控中的.有关表空间大小超过某个警戒值.

发现 SYSAUX表空间超过了15GB

通过以下代码查看SYSAUX表空间的功能占用情况

SELECT occupant_name "Item",
       space_usage_kbytes / 1048576 "Space Used (GB)",
       schema_name "Schema",
       move_procedure "Move Procedure"
  FROM v$sysaux_occupants
ORDER BY 2 desc

基本来之于

Item	Space Used (GB)	Schema
SM/AWR	15.3005981445313	SYS

查看对应表和索引大小排行榜

SELECT *
  FROM (SELECT SEGMENT_NAME,
               PARTITION_NAME,
               SEGMENT_TYPE,
               BYTES / 1024 / 1024
          FROM DBA_SEGMENTS
         WHERE TABLESPACE_NAME = 'SYSAUX'
         ORDER BY 4 DESC)
 WHERE ROWNUM <= 10;

SEGMENT_NAME PARTITION_NAME SEGMENT_TYPE BYTES/1024/1024
WRH$_LATCH_CHILDREN WRH$_LATCH__567344007_15885 TABLE PARTITION 3971
WRH$_LATCH_CHILDREN_PK WRH$_LATCH__567344007_15885 INDEX PARTITION 2822
WRH$_LATCH_CHILDREN WRH$_LATCH__567344007_0 TABLE PARTITION 2213
WRH$_LATCH_CHILDREN WRH$_LATCH__567344007_15909 TABLE PARTITION 1984
WRH$_LATCH_CHILDREN_PK WRH$_LATCH__567344007_0 INDEX PARTITION 1537
WRH$_LATCH_CHILDREN_PK WRH$_LATCH__567344007_15909 INDEX PARTITION 1412

基本上都是 WRH$表的分区过大  当中 WRH$_LATCH__567344007_15909  第一个数字是DBID 第二数字是快照ID.

须要检查上面 15885 15909 0 三个ID 是否是近期的ID?

查看ID的时间 发现 是近期2天的ID

select snap_id, begin_interval_time from sys.dba_hist_snapshot order by snap_id;

是不是 把STATISTICS_LEVEL 设置了ALL 导致他们变大了呢?

只是关怎样 我们把 0给清空掉!

Alter table WRH$_LATCH_CHILDREN truncate partition WRH$_LATCH__567344007_0;

把原来默认AWR 保留31天 改成保留10天

select dbms_stats.get_stats_history_retention from dual;

exec dbms_stats.alter_stats_history_retention(10);

清空掉 11天的统计信息

exec dbms_stats.purge_stats(systimestamp -11);

说实在的 这些统计信息占空间不多, 仅仅是为了保持一致行. 库大了保留31天是否非常不划算的事.