Analyze database activity using v$log_history

Latest posts by Cyrille Modiano (see all)

The v$log_history view contains important information on how application’s users use the database , this view can help you define periods with the most activity in the database.

v$log_history queries

You can adapt the query to your needs, you just have to change the way you format the date to be able to drilldown to the precision you want.

select round(avg(LOG_SWITCHES)) LOG_SWITCHES, DAY 
from (
		select to_char(trunc(first_time), 'Day') DAY, TRUNC(FIRST_TIME, 'DDD'), count(*) LOG_SWITCHES
		from v$log_history 
		group by TRUNC(FIRST_TIME, 'DDD'), to_char(trunc(first_time), 'Day')
		order by 2
	 )
group by day;

This one gives the following output :

LOG_SWITCHES DAY
------------ ---------
207 Sunday
212 Monday
218 Friday
192 Thursday
207 Wednesday
216 Tuesday
209 Saturday

You can find out which day of the week is the most active. You can also have a day to day analysis for the last month :

select round(avg(LOG_SWITCHES)) LOG_SWITCHES, DAY 
from (
		select TRUNC(FIRST_TIME, 'DDD') DAY, count(*) LOG_SWITCHES
		from v$log_history 
		where first_time between sysdate -30 and sysdate
		group by TRUNC(FIRST_TIME, 'DDD'), to_char(trunc(first_time), 'Day')
		order by 1
	 )
group by day
order by 2;

here is the output :

LOG_SWITCHES DAY
------------ ---------
91 10-AUG-15
225 11-AUG-15
233 12-AUG-15
224 13-AUG-15
221 14-AUG-15
218 15-AUG-15
217 16-AUG-15
225 17-AUG-15
218 18-AUG-15
215 19-AUG-15
212 20-AUG-15
203 21-AUG-15
198 22-AUG-15
198 23-AUG-15
200 24-AUG-15
201 25-AUG-15
202 26-AUG-15
202 27-AUG-15
190 28-AUG-15
150 29-AUG-15
151 30-AUG-15
153 31-AUG-15
182 01-SEP-15
202 02-SEP-15
201 03-SEP-15
203 04-SEP-15
203 05-SEP-15
199 06-SEP-15
202 07-SEP-15
205 08-SEP-15
124 09-SEP-15

 

You can also drilldown to hours in the day :

select Hour , round(avg(LOG_SWITCHES)) LOG_SWITCHES
from (
		select to_char(trunc(first_time, 'HH'),'HH24') Hour, TRUNC(FIRST_TIME, 'DDD'), count(*) LOG_SWITCHES
		from v$log_history 
		group by TRUNC(FIRST_TIME, 'DDD'), trunc(first_time, 'HH')
		order by 1
	 )
group by Hour
order by Hour;

Here the output :

HO LOG_SWITCHES
-- ------------
00 8
01 9
02 8
03 8
04 25
05 7
06 8
07 8
08 8
09 8
10 8
11 8
12 8
13 8
14 8
15 8
16 8
17 8
18 8
19 7
20 8
21 7
22 8
23 15

Be creative 🙂

3 thoughts on “Analyze database activity using v$log_history

    1. Hi,

      This analysis allows you to understand how your database is used, what are the most active hours and which ones have the least activity.
      This information allows you to:

      – Know when there is unusual activity on your database based on the usual usage data.
      – know at what hours it is possible to do maintenance by impacting the least users.

      Cyrille

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.