DB Time (2 of 3) (ENG)

Here the Italian version

DB Time (1 of 3)
DB Time (3 of 3) (soon)

DB Time = CPU Time + Wait Time

is the equation that ties the main components of the database:
- work time
- wait time

You can rewrite this equation as (you divide by DB Time and multiply by 100)

100 = (CPU Time/DB Time)*100 + (Wait Time/DB time)*100

This is the way the "AWR" shows us the "Top Timed Events". Let's see. The example that follows, is taken from one of the last tuning I made on a version of Oracle 10g

• AWR Report - 10.2.0.5 Version

 

  

 

DB Time = 440 mins = 26400 secs

log file switch (checkpoint incoplete)	11908 / 26400 => 0,45106 => 45,1%
gc buffer busy	5376 / 26400 => 0,20363636 => 20,4
PX Deq Credit: send blkd	1537 / 26400 => 0,058219696 => 5,8%
buffer busy waits	1358 / 26400 => 0,0514393939 => 5,1%

In later versions, the name of the column containing the percentage (second from right) "% DB Time"
 

• AWR Report - 11.2.0.4 Version

   

  

DB Time = 498 mins = 29880 secs

db file sequential read	2736 / 29880 => 0,09156 => 9,15%
db file scattered read	1753 / 29880 => 0,05866 => 5,86%
log file sync	1500 / 29880 => 0,05020 => 5,02%
row cache lock	1096 / 29880 => 0,03668 => 3,67%

• AWR Report - 12.1.0.2 Version

 

 

DB Time = 21 mins = 1260 secs

db file sequential read	57,5 / 1260 => 0,04563 => 4,56%
rdbms ipc reply	50,7 / 1270 => 0,04023 => 4,02%
DFS lock handle	18,2 / 1270 => 0,01433 => 1,43%
log file sync	13,6 / 1270 => 0,01070 => 1,07%

DB Time (1 of 3) DB Time (2 of 3) (soon)