A log switch occurs when LGWR stops writing to one redo log group and
starts writing to another. By default, a log switch occurs
automatically when the current redo log file group fills.
More frequently log switch will cause performance problem in oracle database. DBA has to monitor log switch frequency and per hour this value should be less than 6 or 8.
Below script will give log switch frequency map for oracle database.
SELECT
SUBSTR(TO_CHAR(first_time, 'MM/DD/RR HH:MI:SS'),1,5) "DAY(Month/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$log_history a
GROUP BY SUBSTR(TO_CHAR(first_time, 'MM/DD/RR HH:MI:SS'),1,5)
ORDER BY SUBSTR(TO_CHAR(first_time, 'MM/DD/RR HH:MI:SS'),1,5) desc
Also you can check average log switch per minute value with query below
WITH redo_log_switch_times AS
(SELECT sequence#, first_time,
LAG (first_time, 1) OVER (ORDER BY first_time) AS LAG,
first_time
- LAG (first_time, 1) OVER (ORDER BY first_time) lag_time,
1440
* (first_time - LAG (first_time, 1) OVER (ORDER BY first_time)
) lag_time_pct_mins
FROM v$log_history
ORDER BY sequence#)
SELECT round(AVG (lag_time_pct_mins),2) avg_log_switch_per_min
FROM redo_log_switch_times;
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Monday, December 17, 2012
Sunday, December 16, 2012
Purging Strategy in Oracle E-Business Suite -3- (FNDSCPRG)
Concurrent Program Shortname is FNDSCPRG
Program Name is "Purge Signon Audit Data Concurrent Program"
This concurrent program purge tables listed below.
FND_LOGIN_RESP_FORMS
FND_LOGIN_RESPONSIBILITIES
FND_LOGINS
FND_UNSUCCESSFUL_LOGINS
Program Name is "Purge Signon Audit Data Concurrent Program"
This concurrent program purge tables listed below.
FND_LOGIN_RESP_FORMS
FND_LOGIN_RESPONSIBILITIES
FND_LOGINS
FND_UNSUCCESSFUL_LOGINS
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