PX Deq Waits

From: deen dayal <deen.dayal_at_dol.state.nj.us>
Date: Tue, 04 May 2004 17:24:45 -0400
Message-id: <1083705885.23477.8.camel@oralinux>

Hi,

I ran statspack report against one of my production databases(9.2.0.3) and following is part of it.

Top 5 Timed Events

~~~~~~~~~~~~~~~~~~                                                     % Total
Event                                               Waits    Time (s) Ela Time
-------------------------------------------- ------------ ----------- --------
CPU time                                                        1,596    55.05
PX Deq: Table Q qref                                  496         991    34.20
db file sequential read                            25,700         143     4.95
db file scattered read                             22,133         104     3.58
latch free                                          2,015          28      .96
         -------------------------------------------------------------

34.2% of time is spent on "PX Deq: Table Q qref", I do not know any thing about this event. I searched metalink, did not find much except that it is a parallel query related.

The weird thing is we do not run much of parallel queries and yet this event appears on the report every time I run it.

Does anybody know any thing about this wait event??

Here is my Instance Summary from statspack report

Instance Efficiency Percentages (Target 100%)

            Buffer Nowait %:  100.00       Redo NoWait %:              100.00
            Buffer  Hit   %:   92.21    In-memory Sort %:              100.00
            Library Hit   %:   98.13        Soft Parse %:               93.91
         Execute to Parse %:    1.41         Latch Hit %:               99.79
Parse CPU to Parse Elapsd %:   78.44     % Non-Parse CPU:               95.70

 Shared Pool Statistics        Begin   End
                               ------  ------
             Memory Usage %:   77.89   75.72

% SQL with executions>1: 66.56 72.19 % Memory for SQL w/exec>1: 99.59 99.59

Thanks
Deen

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Received on Tue May 04 2004 - 16:22:28 CDT