Database Reference
In-Depth Information
I ran the test in single user mode (that is, by itself with no other active database sessions), and the Statspack
report came back with this information:
Elapsed: 0.25 (mins) Av Act Sess: 0.9
DB time: 0.22 (mins) DB CPU: 0.20 (mins)
Cache Sizes Begin End
~~~~~~~~~~~ ---------- ----------
Buffer Cache: 2,656M Std Block Size: 8K
Shared Pool: 640M Log Buffer: 14,808K
Load Profile Per Second Per Transaction Per Exec Per Call
~~~~~~~~~~~~ ------------------ ----------------- ----------- -----------
...
Parses: 3,342.1 25,066.0
Hard parses: 1,667.2 12,504.0
...
Instance Efficiency Indicators
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Buffer Nowait %: 100.00 Redo NoWait %: 100.00
Buffer Hit %: 99.99 Optimal W/A Exec %: 100.00
Library Hit %: 60.05 Soft Parse %: 50.12
Execute to Parse %: 0.11 Latch Hit %: 100.00
Parse CPU to Parse Elapsd %: 108.72 % Non-Parse CPU: 16.29
...
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time
----------------------------------------- ------------ ----------- ------ ------
AQPC idle 1 30 30010 36.1
heartbeat redo informer 15 15 1004 18.1
LGWR worker group idle 14 15 1055 17.8
lreg timer 4 12 3001 14.4
CPU time 11 13.4
I included the SGA configuration for reference, but the relevant statistics are as follows:
Elapsed (DB time) time of approximately 15 seconds (0.25 of a minute)
1,667 hard parses per second
Now, if we were to run two of these programs simultaneously, we might expect the hard parsing to jump to
about 3,300 per second (we have two CPUs available, after all) and the CPU time to double to perhaps 22 CPU
seconds. Let's take a look:
11 CPU seconds used
Elapsed: 0.27 (mins) Av Act Sess: 1.6
DB time: 0.44 (mins) DB CPU: 0.41 (mins)
...
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