SYSAUX表空间过大处理

http://ylw6006.blog.51cto.com/470441/1135593/

一般来讲除开业务数据存放的表空间，DBA要着重关注SYSTEM,SYSAUX,UNDO,TEMP表空间，SYSTEM表空间的大小一般是衡定的，UNDO和TEMP表空间的大小由数据库的业务情况决定，而SYSAUX表空间在默认条件下你如果不做任何配置，随着时间的推移，会膨胀的越来越大！SYSAUX表空间做为SYSTEM表空间的辅助表空间，主要存放EM相关的内容以及表统计信息，AWR快照，审计信息等，个人认为，如果你的SYSAUX表空间大小超过2G，那么该考虑让他减肥了！ 

一：使用下列语句查询表空间使用率 

SELECT * FROM (
SELECT D.TABLESPACE_NAME,
        SPACE || 'M' "SUM_SPACE(M)",
        BLOCKS "SUM_BLOCKS",
        SPACE - NVL (FREE_SPACE, 0) || 'M' "USED_SPACE(M)",
        ROUND ( (1 - NVL (FREE_SPACE, 0) / SPACE) * 100, 2) || '%'
           "USED_RATE(%)",
        FREE_SPACE || 'M' "FREE_SPACE(M)"
   FROM (  SELECT TABLESPACE_NAME,
                  ROUND (SUM (BYTES) / (1024 * 1024), 2) SPACE,
                  SUM (BLOCKS) BLOCKS
             FROM DBA_DATA_FILES
         GROUP BY TABLESPACE_NAME) D,
        (  SELECT TABLESPACE_NAME,
                  ROUND (SUM (BYTES) / (1024 * 1024), 2) FREE_SPACE
             FROM DBA_FREE_SPACE
         GROUP BY TABLESPACE_NAME) F
  WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME(+)
 UNION ALL
 SELECT D.TABLESPACE_NAME,
        SPACE || 'M' "SUM_SPACE(M)",
        BLOCKS SUM_BLOCKS,
        USED_SPACE || 'M' "USED_SPACE(M)",
        ROUND (NVL (USED_SPACE, 0) / SPACE * 100, 2) || '%' "USED_RATE(%)",
        NVL (FREE_SPACE, 0) || 'M' "FREE_SPACE(M)"
   FROM (  SELECT TABLESPACE_NAME,
                  ROUND (SUM (BYTES) / (1024 * 1024), 2) SPACE,
                  SUM (BLOCKS) BLOCKS
             FROM DBA_TEMP_FILES
         GROUP BY TABLESPACE_NAME) D,
        (  SELECT TABLESPACE_NAME,
                  ROUND (SUM (BYTES_USED) / (1024 * 1024), 2) USED_SPACE,
                  ROUND (SUM (BYTES_FREE) / (1024 * 1024), 2) FREE_SPACE
             FROM V$TEMP_SPACE_HEADER
         GROUP BY TABLESPACE_NAME) F
  WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME(+)
 ORDER BY 1)
 WHERE TABLESPACE_NAME IN ('SYSAUX','SYSTEM','UNDOTBS1','TEMP');

二：查询SYSAUX表空间内各个分类项目占存储空间的比重，很明显可以看出来AWR快照占用了2G左右的空间，统计信息为149M左右，同时数据库关闭了审计audit_trail，所以审计表aud$不占空间 

SELECT occupant_name "Item",
       space_usage_kbytes / 1048576 "Space Used (GB)",
       schema_name "Schema",
       move_procedure "Move Procedure"
  FROM v$sysaux_occupants
ORDER BY 1

三：修改统计信息的保持时间，默认为31天，这里修改为7天，过期的统计信息会自动被删除

SQL> select dbms_stats.get_stats_history_retention from dual;

GET_STATS_HISTORY_RETENTION
---------------------------
                         31

SQL> exec dbms_stats.alter_stats_history_retention(7);
PL/SQL procedure successfully completed.

SQL> select dbms_stats.get_stats_history_retention from dual;

GET_STATS_HISTORY_RETENTION
---------------------------
                          7

四：修改AWR快照的保存时间为7天(7*24*60),每小时收集一次，也可以通过EM界面查看和修改

SQL> begin
         dbms_workload_repository.modify_snapshot_settings (
            interval => 60,
            retention => 10080,
            topnsql => 100
          );
end;

五：删除AWR快照，再次查看SYSAUX表空间使用率,最后表空间使用率降低为38.42%

select min(snap_id),max(snap_id) from dba_hist_snapshot;//查询最最小和最大快照ID

begin
     dbms_workload_repository.drop_snapshot_range(
       low_snap_id => 10758,
      high_snap_id => 10900,
      dbid => 387090299);
end;