– 看下redo日志切换情况
SELECT SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH:MI:SS’),1,5) Day,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘00’,1,0)) H00,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘01’,1,0)) H01,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘02’,1,0)) H02,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘03’,1,0)) H03,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘04’,1,0)) H04,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘05’,1,0)) H05,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘06’,1,0)) H06,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘07’,1,0)) H07,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘08’,1,0)) H08,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘09’,1,0)) H09,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘10’,1,0)) H10,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘11’,1,0)) H11,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘12’,1,0)) H12,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘13’,1,0)) H13,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘14’,1,0)) H14,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘15’,1,0)) H15,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘16’,1,0)) H16,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘17’,1,0)) H17,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘18’,1,0)) H18,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘19’,1,0)) H19,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘20’,1,0)) H20,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘21’,1,0)) H21,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘22’,1,0)) H22,
SUM(DECODE(SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH24:MI:SS’),10,2),‘23’,1,0)) H23,
COUNT(*) TOTAL
FROM v$log_history a
WHERE first_time>=to_char(sysdate-10)
GROUP BY SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH:MI:SS’),1,5)
ORDER BY SUBSTR(TO_CHAR(first_time, ‘MM/DD/RR HH:MI:SS’),1,5) DESC;

查看最近2小时"块改变"最多的segment
select *
from (SELECT to_char(begin_interval_time, ‘YYYY_MM_DD HH24:MI’) snap_time,
dhsso.object_name,
SUM(db_block_changes_delta)
FROM dba_hist_seg_stat dhss,
dba_hist_seg_stat_obj dhsso,
dba_hist_snapshot dhs
WHERE dhs.snap_id = dhss.snap_id
AND dhs.instance_number = dhss.instance_number
AND dhss.obj# = dhsso.obj#
AND dhss.dataobj# = dhsso.dataobj#
AND begin_interval_time > sysdate - 120 / 1440
GROUP BY to_char(begin_interval_time, ‘YYYY_MM_DD HH24:MI’),
dhsso.object_name
order by 3 desc)
where rownum <= 5;