Archive/Redo Log generation

Redo Log Generation

See how much redo logs you are generating per day. Good to use when you see your archivelog directories are filling up unusually.


This will not show you where the problem is though, will just give you the number of log switches and average MB generated per day so that you can compare day by day. If you do start seeing unusually high log switches, thus high volume of archivelog generation, maybe a good place to start is looking for transactions which do lots of UPDATE/DELETE operations in the STATSPACK/AWR.

Archive generation:

SELECT TO_CHAR(FIRST_TIME,'YYYY-MM-DD') DAY,
TO_CHAR(FIRST_TIME,'HH24') HOUR,
COUNT(*) TOTAL
FROM V$LOG_HISTORY
GROUP BY TO_CHAR(FIRST_TIME,'YYYY-MM-DD'),TO_CHAR(FIRST_TIME,'HH24')
ORDER BY TO_CHAR(FIRST_TIME,'YYYY-MM-DD'),TO_CHAR(FIRST_TIME,'HH24')
ASC;

DAILY ARCHIVE LOG GENERATION IN GB :

Hourly/Daily Archive generation
The below query comes handy to understand the archivelog generation of an Oracle database on an hourly /daily basis, per thread – in case of RAC databases.

Archivelog generation on a daily basis:

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set pages 1000
select trunc(COMPLETION_TIME,'DD') Day, thread#, round(sum(BLOCKS*BLOCK_SIZE)/1048576) MB,count(*) Archives_Generated from v$archived_log
group by trunc(COMPLETION_TIME,'DD'),thread# order by 1;
Archive log generation on an hourly basis:

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set pages 1000
select trunc(COMPLETION_TIME,'HH') Hour,thread# , round(sum(BLOCKS*BLOCK_SIZE)/1048576) MB,count(*) Archives from v$archived_log
group by trunc(COMPLETION_TIME,'HH'),thread#  order by 1 ;
Sample output:

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HOUR                   THREAD#         MB   ARCHIVES
------------------- ---------- ---------- ----------
2009 08 20 12:00:00          1      31268        339
2009 08 20 13:00:00          1       4994         55
2009 08 20 14:00:00          1       4412         48
2009 08 20 15:00:00          1       4805         52
2009 08 20 16:00:00          1       3364         37
2009 08 20 17:00:00          1         22          1
2009 08 20 21:00:00          1          9          1

Also, the following script is useful to find the archivelog switches on an hourly basis that happened in the past one week.


SELECT to_date(first_time) DAY,
to_char(sum(decode(to_char(first_time,'HH24'),'00',1,0)),'99') "00",
to_char(sum(decode(to_char(first_time,'HH24'),'01',1,0)),'99') "01",
to_char(sum(decode(to_char(first_time,'HH24'),'02',1,0)),'99') "02",
to_char(sum(decode(to_char(first_time,'HH24'),'03',1,0)),'99') "03",
to_char(sum(decode(to_char(first_time,'HH24'),'04',1,0)),'99') "04",
to_char(sum(decode(to_char(first_time,'HH24'),'05',1,0)),'99') "05",
to_char(sum(decode(to_char(first_time,'HH24'),'06',1,0)),'99') "06",
to_char(sum(decode(to_char(first_time,'HH24'),'07',1,0)),'99') "07",
to_char(sum(decode(to_char(first_time,'HH24'),'08',1,0)),'99') "08",
to_char(sum(decode(to_char(first_time,'HH24'),'09',1,0)),'99') "09",
to_char(sum(decode(to_char(first_time,'HH24'),'10',1,0)),'99') "10",
to_char(sum(decode(to_char(first_time,'HH24'),'11',1,0)),'99') "11",
to_char(sum(decode(to_char(first_time,'HH24'),'12',1,0)),'99') "12",
to_char(sum(decode(to_char(first_time,'HH24'),'13',1,0)),'99') "13",
to_char(sum(decode(to_char(first_time,'HH24'),'14',1,0)),'99') "14",
to_char(sum(decode(to_char(first_time,'HH24'),'15',1,0)),'99') "15",
to_char(sum(decode(to_char(first_time,'HH24'),'16',1,0)),'99') "16",
to_char(sum(decode(to_char(first_time,'HH24'),'17',1,0)),'99') "17",
to_char(sum(decode(to_char(first_time,'HH24'),'18',1,0)),'99') "18",
to_char(sum(decode(to_char(first_time,'HH24'),'19',1,0)),'99') "19",
to_char(sum(decode(to_char(first_time,'HH24'),'20',1,0)),'99') "20",
to_char(sum(decode(to_char(first_time,'HH24'),'21',1,0)),'99') "21",
to_char(sum(decode(to_char(first_time,'HH24'),'22',1,0)),'99') "22",
to_char(sum(decode(to_char(first_time,'HH24'),'23',1,0)),'99') "23"
from
v$log_history
where to_date(first_time) > sysdate -8
GROUP by
to_char(first_time,'YYYY-MON-DD'), to_date(first_time)
order by to_date(first_time)
/