-- #############################################################################################
--
-- %Purpose: Tuning Redologs und Checkpoints (Contention, Waits, Number/Duration of Checkpoints)
--
-- #############################################################################################
1). Redolog Buffer Contention
-----------------------------
SELECT SUBSTR(name,1,20) "Name",gets,misses,immediate_gets,immediate_misses
FROM v$latch
WHERE name in ('redo allocation', 'redo copy');
Name GETS MISSES IMMEDIATE_GETS IMMEDIATE_MISSES
-------------------- ---------- ---------- -------------- ----------------
redo allocation 277'446'780 2'534'627 0 0
redo copy 33'818 27'694 357'613'861 150'511
MISSES/GETS (must be < 1%)
Redo allocation: (2'534'627 / 277'446'780) * 100 = 0.91 %
Redo Copy: (27'694 / 33'818) * 100 = 81.8 %
IMMEDIATE_MISSES/(IMMEDIATE_GETS+IMMEDIATE_MISSES) (must be < 1%)
Redo Copy: 150'511/(150'511+357'613'861) = 0.04 %
2). Waits on Redo Log Buffer
----------------------------
SELECT name,value
FROM v$sysstat
WHERE name = 'redo log space requests';
The value of 'redo log space requests' reflects the number
of times a user process waits for space in the redo log buffer.
Optimal is if the value is near 0 (Oracle Manual says this ...)
NAME VALUE
---------------------------------------------------------------- ----------
redo log space requests 22641
4). Number of Checkpoints per hour
----------------------------------
set feed off;
set pagesize 10000;
set wrap off;
set linesize 200;
set heading on;
set tab on;
set scan on;
set verify off;
--
spool show_logswitches.lst
ttitle left 'Redolog File Status from V$LOG' skip 2
select group#, sequence#,
Members, archived, status, first_time
from v$log;
ttitle left 'Number of Logswitches per Hour' skip 2
select to_char(first_time,'YYYY.MM.DD') day,
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'00',1,0)),'99') "00",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'01',1,0)),'99') "01",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'02',1,0)),'99') "02",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'03',1,0)),'99') "03",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'04',1,0)),'99') "04",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'05',1,0)),'99') "05",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'06',1,0)),'99') "06",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'07',1,0)),'99') "07",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'08',1,0)),'99') "08",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'09',1,0)),'99') "09",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'10',1,0)),'99') "10",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'11',1,0)),'99') "11",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'12',1,0)),'99') "12",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'13',1,0)),'99') "13",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'14',1,0)),'99') "14",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'15',1,0)),'99') "15",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'16',1,0)),'99') "16",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'17',1,0)),'99') "17",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'18',1,0)),'99') "18",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'19',1,0)),'99') "19",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'20',1,0)),'99') "20",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'21',1,0)),'99') "21",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'22',1,0)),'99') "22",
to_char(sum(decode(substr(to_char(first_time,'DDMMYYYY:HH24:MI'),10,2),'23',1,0)),'99') "23"
from v$log_history
group by to_char(first_time,'YYYY.MM.DD')
/
spool off;
DAY 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
----- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
07/07 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 0 0 0 0 0 0 0 0
07/08 0 0 0 0 0 0 0 0 0 0 0 5 0 4 1 0 1 0 0 0 0 0 0 0
07/12 0 0 0 0 0 0 0 0 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0 0
07/13 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0
07/14 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0
07/15 1 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 1 2 2 0 0 0 0 0
07/16 0 0 10 10 15 11 5 0 0 0 0 0 2 5 5 4 5 7 6 6 7 4 4 4
07/17 2 2 1 3 4 6 9 10 11 11 12 12 11 11 12 11 11 12 12 9 9 10 12 9
07/18 12 9 10 10 8 8 9 10 9 8 9 10 10 11 10 11 10 10 11 10 11 9 10 10
07/19 9 3 1 1 0 0 4 6 7 7 4 5 11 10 5 4 5 7 6 8 7 5 5 3
07/20 1 1 8 10 7 5 4 5 4 5 7 7 9 7 9 9 7 9 10 11 12 11 12 9
07/21 9 10 10 10 12 10 7 8 9 8 9 10 11 11 11 8 10 10 12 7 6 7 7 7
07/22 8 7 9 10 8 6 7 8 8 8 9 9 9 10 9 9 9 9 9 9 10 7 6 7
07/23 5 5 7 7 7 2 3 3 4 5 6 5 5 4 3 3 4 4 6 6 5 9 8 5
07/24 4 4 5 4 7 6 5 8 8 11 11 11
log_checkpoint_interval = 900'000'000 (OK, must be greather than Redolog-File)
log_checkpoint_timeout = 1200 (Set it to 0, so time-based checkpoints are disabled)
5). Time needed to write a checkpoint
-------------------------------------
Beginning database checkpoint by background
Mon Aug 2 16:37:36 1999
Thread 1 advanced to log sequence 2860
Current log# 4 seq# 2860 mem# 0: /data/ota/db1/OTASICAP/redo/redoOTASICAP04.log
Mon Aug 2 16:43:31 1999
Completed database checkpoint by background
==> 6 Minutes
Mon Aug 2 16:45:15 1999
Beginning database checkpoint by background
Mon Aug 2 16:45:15 1999
Thread 1 advanced to log sequence 2861
Current log# 5 seq# 2861 mem# 0: /data/ota/db1/OTASICAP/redo/redoOTASICAP05.log
Mon Aug 2 16:50:29 1999
Completed database checkpoint by background
==> 5.5 Minutes
Mon Aug 2 16:51:50 1999
Beginning database checkpoint by background
Mon Aug 2 16:51:51 1999
Thread 1 advanced to log sequence 2862
Current log# 6 seq# 2862 mem# 0: /data/ota/db1/OTASICAP/redo/redoOTASICAP06.log
Mon Aug 2 16:56:44 1999
Completed database checkpoint by background
==> 5.5 Minutes
↧
Steps to Tune Redologs undo Checkpoints for Contention,Waits and Number/Duration of Checkpoints
↧