RE: Negative wait time

  • From: "Cary Millsap" <cary.millsap@xxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Mon, 2 Feb 2004 09:48:16 -0600

Quantization error.

The error is greater on the 'c' statistic than any other, because it is
obtained by polling in 10,000-microsecond increments.


Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Jamadagni, Rajendra
Sent: Monday, February 02, 2004 8:03 AM
To: Oracle List (E-mail)
Subject: Negative wait time

Okay it is Monday and I seem to have difficulty remembering stuff  ...
I wrote a pl/sql procedure that analyzes a given trace file and produces
output like this ... but look at wait time ... why is it < 0 ?? 
wait = elapsed-cpu right? What am I missing? In case you are wondering
... this procedure (and its output) is based on Cary's paper 'LIO Vs
PIO' ... not precise, but should be pretty close.

SQL Hash Value : 98525727
SELECT count(distinct(us.Ut_Id)) Res_Prmpt
    From yyyy ms, zzzz us
   Where ms.Mg_Unit_Id = us.Ut_Id
     And us.Pob_Id = :b4
     and ( :b3 IS NULL OR us.Line_Number = :b3 )
     And us.Monday_Dt between :b2 AND :b1
     And us.Makegood = 'A'
     And us.Reason_Cd <> -19
     And ms.Mg_Unit_Type = 'P'
     And us.Ut_Id Not In (Select ms1.Mg_Unit_Id
                            From xxxx ms1, yyyy mh
                           Where ms1.Mg_Number = mh.Mg_Number
                             And ms1.Mg_Unit_Type = 'M'
                             And mh.Mg_Pob_Id = :b4
                             And mh.Mg_Line_Number = us.Line_Number)

                        -------- Response  Time --------
Action  Count      Rows   Ela Time   CPU Time  Wait Time LIO Blocks PIO
Blocks
------ ------ --------- ---------- ---------- ---------- ----------
----------
PARSE       1         0      0.000      0.000      0.000          0
0
EXEC       51         0      0.004      0.010     -0.006          0
0
FETCH      51        51      0.450      0.390      0.060       9047
11
------ ------ --------- ---------- ---------- ---------- ----------
----------
TOTAL     103        51      0.454      0.400      0.054       9047
11


Any pointers are welcome, and yes please excuse me while I go have
another coffee.
Raj
------------------------------------------------------------------------
--------
Rajendra dot Jamadagni at nospamespn dot com
All Views expressed in this email are strictly personal.
QOTD: Any clod can have facts, having an opinion is an art !


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