Database Reference
In-Depth Information
Resource Usage Profile
**********************
Total Number of Duration per
Component Duration [s] % Events Events [s]
----------------------- ------------ ------- --------- ------------
CPU 6.493 53.071 n/a n/a
db file scattered read 2.792 22.818 530 0.005
direct path read temp 2.417 19.753 24,015 0.000
direct path write temp 0.513 4.194 11,002 0.000
recursive statements
0.020
0.161
n/a n/a
db file sequential read 0.000 0.002 2 0.000
----------------------- ------------ -------
Total 12.234 100.000
6 recursive statements were executed.
Total
Statement ID Type Duration [s] %
------------ ---------------------- ------------ -------
#4 SELECT (SYS recursive) 0.015 0.121
#6 SELECT (SYS recursive) 0.004 0.032
#10 SELECT (SYS recursive) 0.001 0.008
#13 SELECT (SYS recursive) 0.000 0.001
#17 SELECT (SYS recursive) 0.000 0.000
#18 SELECT (SYS recursive) 0.000 0.000
------------ ---------------------- ------------ -------
Total 0.006 0.050
In the resource usage profiles shown up to now, wait events are just summarized. To have additional information,
a histogram like the following is provided for every component of the resource usage profile. In this case, the statistics
are related to the
db file scattered read
wait event of SQL statement 2. Notice how the wait events are grouped by
their duration (
Range
column). For example, you see that about 52 percent of the wait events lasted between 4,096 and
8,192 microseconds. Because the
db file scattered read
wait event is associated with multiblock reads, it might
also be useful to see the average number of blocks read by a disk I/O operation (
Blocks per Event
column):
Total Number of Duration per Blocks per
Range [µs] Duration % Events % Event [µs] Blocks Event
------------------------ -------- ------- --------- ------- ------------ ------ ----------
256
≥
duration < 512 0.003 0.111 7 1 443 56 8
512
≥
duration < 1024 0.008 0.288 9 2 892 72 8
1024
≥
duration < 2048 0.033 1.191 18 3 1,847 826 46
2048
≥
duration < 4096 0.517 18.525 166 31 3,115 11,627 70
4096
≥
duration <
8192
1.465
52.459
264 50 5,547 20,742 79
8192
≥
duration < 16384 0.579 20.736 60 11 9,648 4,722 79
16384
≥
duration < 32768 0.126 4.496 5 1 25,101 336 67
32768
≥
duration < 65536 0.061 2.195 1 0 61,274 81 81
------------------------ -------- ------- --------- ------- ------------ ------ ----------
Total 2.792 100.000 530 100.000 5,267 38,462 73
If the display of detailed information is enabled (the
wait
argument is used for that purpose), further details
might be provided in addition to the previous histogram. This strongly depends on the type of wait event. Actually,
