Can we trust these numbers ?

  • From: robson@xxxxxxxxxxxxxxx
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 25 Aug 2004 13:53:51 -0300

Hi

I am intrigued that sometimes I get statspack reports that show very bi=
g
figures on the event wait
times.
Look the total wait time of the latch free: 56,629,674,849 cs.
It gives one average time of 1,029,784 ms or 1030 seconds (17 hours).
What can be wrong ?

Thanks for any hint


STATSPACK report for

DB Name         DB Id    Instance     Inst Num Release     OPS Host
------------ ----------- ------------ -------- ----------- --- --------=
----
XPTO          1234567890 xptoinst            1 8.1.7.4.0   NO  XPTOHOST=

                Snap Id     Snap Time      Sessions
                ------- ------------------ --------
 Begin Snap:      27474 23-Aug-04 09:58:58    1,776
   End Snap:      27475 23-Aug-04 10:59:10    1,776
    Elapsed:                  60.20 (mins)

Cache Sizes
~~~~~~~~~~~
           db_block_buffers:    2097152          log_buffer:    1572864=

              db_block_size:       8192    shared_pool_size: 1825361100=


Load Profile
~~~~~~~~~~~~                              Per Second         Per
Transaction
                                     ---------------
---------------
                  Redo size:              316,789.22
3,949.25
              Logical reads:              214,536.95
2,674.52
              Block changes:                1,972.78
24.59
             Physical reads:                4,325.08
53.92
            Physical writes:                  356.58
4.45
                 User calls:                2,351.87
29.32
                     Parses:                  630.83
7.86
                Hard parses:                   10.49
0.13
                      Sorts:                  719.67
8.97
                     Logons:                    0.95
0.01
                   Executes:                1,665.18
20.76
               Transactions:                   80.22

  % Blocks changed per Read:        0.92    Recursive Call %:       32.=
19
 Rollback per transaction %:        0.05       Rows per Sort:       15.=
17

Instance Efficiency Percentages (Target 100%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Buffer Nowait %:       99.99       Redo NoWait %:      100.=
00
            Buffer  Hit   %:       97.98    In-memory Sort %:       99.=
99
            Library Hit   %:       99.46        Soft Parse %:       98.=
34
         Execute to Parse %:       62.12         Latch Hit %:       99.=
71
Parse CPU to Parse Elapsd %:        0.00     % Non-Parse CPU:       99.=
93

 Shared Pool Statistics           Begin       End
                                  ------      ------
             Memory Usage %:       86.70       84.48
    % SQL with executions>1:       76.18       74.04
  % Memory for SQL w/exec>1:       68.50       70.51

Top 5 Wait Events
~~~~~~~~~~~~~~~~~                                               Wait
% Total
Event                                               Waits    Time (cs)
Wt Time
-------------------------------------------- ------------ -------------=
---
----------
latch free                                        549,918   56,629,674,=
849
67.75
log file sync                                     314,641   11,716,563,=
756
14.02
db file sequential read                         7,527,206   11,331,652,=
411
13.56
rdbms ipc reply                                     2,192    1,952,998,=
207
2.34
db file scattered read                            303,506    1,952,974,=
696
2.34



Robson Gomes


Medidata Inform=E1tica S.A


(21) 2546 3734


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