归档增长过快如何查出原因

1、按天统计归档量，看哪天的归档多

alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
SELECT THREAD#,TRUNC(first_time) "TIME",SUM(block_size*blocks)/1024/1024 "SIZE(MB)"
FROM v$archived_log GROUP BY TRUNC(first_time),THREAD# ORDER BY 1,2;

2、查看日志切换的频率

SELECT    TO_CHAR(FIRST_TIME,'YYYY-MM-DD') DAY,
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'00',1,0)),'999') "00",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'01',1,0)),'999') "01",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'02',1,0)),'999') "02",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'03',1,0)),'999') "03",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'04',1,0)),'999') "04",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'05',1,0)),'999') "05",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'06',1,0)),'999') "06",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'07',1,0)),'999') "07",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'08',1,0)),'999') "08",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'09',1,0)),'999') "09",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'10',1,0)),'999') "10",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'11',1,0)),'999') "11",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'12',1,0)),'999') "12",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'13',1,0)),'999') "13",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'14',1,0)),'999') "14",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'15',1,0)),'999') "15",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'16',1,0)),'999') "16",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'17',1,0)),'999') "17",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'18',1,0)),'999') "18",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'19',1,0)),'999') "19",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'20',1,0)),'999') "20",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'21',1,0)),'999') "21",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'22',1,0)),'999') "22",
                TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME,'HH24'),'23',1,0)),'999') "23"
FROM V$LOG_HISTORY
GROUP BY TO_CHAR(FIRST_TIME,'YYYY-MM-DD') 
ORDER BY 1 DESC;

切换频率与平均值的对比：

WITH T AS 
(
    SELECT TO_CHAR(FIRST_TIME, 'YYYY-MM-DD')    AS LOG_GEN_DAY, 
           TO_CHAR(SUM(DECODE(TO_CHAR(FIRST_TIME, 'YYYY-MM-DD'), 
                       TO_CHAR(FIRST_TIME, 'YYYY-MM-DD'), 1, 0))
                , '999') AS "LOG_SWITCH_NUM"
    FROM   V$LOG_HISTORY 
  WHERE FIRST_TIME < TRUNC(SYSDATE)  --排除当前这一天
    GROUP  BY TO_CHAR(FIRST_TIME, 'YYYY-MM-DD') 
)
SELECT  T.LOG_GEN_DAY
          , T.LOG_SWITCH_NUM
          , M.AVG_LOG_SWITCH_NUM
      , (T.LOG_SWITCH_NUM-M.AVG_LOG_SWITCH_NUM) AS DIFF_SWITCH_NUM
FROM  T CROSS JOIN 
(
    SELECT  TO_CHAR(AVG(T.LOG_SWITCH_NUM),'999') AS AVG_LOG_SWITCH_NUM
    FROM T
) M
ORDER BY T.LOG_GEN_DAY DESC;

3、查找归档比较多的那天，日志切换比较频繁的时段，改变比较多的segment

SELECT to_char(begin_interval_time,'YY-MM-DD HH24') snap_time,
dhso.object_name,
sum(db_block_changes_delta) BLOCK_CHANGED
FROM dba_hist_seg_stat dhss,
dba_hist_seg_stat_obj dhso,
dba_hist_snapshot dhs
WHERE dhs.snap_id = dhss.snap_id
AND dhs.instance_number = dhss.instance_number
AND dhss.obj# = dhso.obj#
AND dhss.dataobj# = dhso.dataobj#
AND begin_interval_time BETWEEN to_date('19-01-22 00:00','YY-MM-DD HH24:MI') 
AND to_date('19-01-22 23:00','YY-MM-DD HH24:MI') 
GROUP BY to_char(begin_interval_time,'YY-MM-DD HH24'),
dhso.object_name
HAVING sum(db_block_changes_delta) > 0
ORDER BY sum(db_block_changes_delta) desc ;

4、定位大量修改segment对应的sql

SELECT to_char(begin_interval_time,'YYYY_MM_DD HH24') WHEN,
dbms_lob.substr(sql_text,4000,1) SQL,
dhss.instance_number INST_ID,
dhss.sql_id,
executions_delta exec_delta,
rows_processed_delta rows_proc_delta
FROM dba_hist_sqlstat dhss,
dba_hist_snapshot dhs,
dba_hist_sqltext dhst
WHERE upper(dhst.sql_text) LIKE '%<segment_name>%' >>>>>>>>>>>>>>>>>> Update the segment name as per the result of previous query result
AND ltrim(upper(dhst.sql_text)) NOT LIKE 'SELECT%'
AND dhss.snap_id=dhs.snap_id
AND dhss.instance_number=dhs.instance_number
AND dhss.sql_id=dhst.sql_id
AND begin_interval_time BETWEEN to_date('11-01-28 13:00','YY-MM-DD HH24:MI') >>>>>>>>>>>> Update time frame as required
AND to_date('11-01-28 14:00','YY-MM-DD HH24:MI') >>>>>>>>>>>> Update time frame as required

EXEC_DELTA---------------------SQL执行的次数。

ROWS_PROC_DELTA---------SQL解析后判断出的，一共涉及的行数。

详见reference

dba_hist_sqlstat

参考：

How to identify the causes of High Redo Generation (文档 ID 2265722.1)

http://www.importnew.com/28503.html

归档增长过快如何查出原因

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