Re: Question about TKPROF output.
- From: "Cary Millsap" <cary.millsap@xxxxxxxxxxxx>
- To: ronnie_doggart@xxxxxxxxx
- Date: Tue, 20 May 2008 14:01:02 -0500
It's a good question. We've long said (e.g., p80 of *Optimizing Oracle
Performance*) that the "disk" figure (which maps to the *p* statistic in the
raw trace data) represents the number of Oracle database blocks obtained by
the database call (in your case, a fetch) via operating system disk read
calls.
But it's possible that it includes "direct path writes," too. I don't know
the answer. A simple test is to run your query again, and this time in
addition to using Oracle's extended SQL trace, use your operating system's
strace tool, as well, upon your session's Oracle kernel process. In the
strace output, you'll be able to see exactly how many blocks are being
manipulated by OS calls, and you'll be able to see the mapping of that
information to your tkprof output.
Cary Millsap
http://method-r.com
http://carymillsap.blogspot.com
On Tue, May 20, 2008 at 7:21 AM, Ronnie Doggart <ronnie_doggart@xxxxxxxxx>
wrote:
> All,
>
> I would just like some clarification on a point:
>
> call count cpu elapsed disk query current
> rows
> ------- ------ -------- ---------- ---------- ---------- ----------
> ----------
> Parse 1 0.00 0.00 0 0 0
> 0
> Execute 1 0.00 0.00 0 0 0
> 0
> Fetch 20 1.01 10.85 6171 7395 0
> 283
> ------- ------ -------- ---------- ---------- ---------- ----------
> ----------
> total 22 1.01 10.85 6171 7395 0
> 283
>
> When the tkprof output shows disk activity of 6171 does this include blocks
> used in one/multi pass hash joins. Are the direct path reads/writes included
> ?
>
> Elapsed times include waiting on following events:
> Event waited on Times Max. Wait Total
> Waited
> ---------------------------------------- Waited ----------
> ------------
> SQL*Net message to client 20 0.00
> 0.00
> db file sequential read 851 0.03
> 2.32
> db file scattered read 341 0.03
> 1.89
> direct path write 312 0.06
> 3.99
> direct path read 312 0.03
> 1.60
> SQL*Net message from client 20 2.27
> 35.33
>
> ********************************************************************************
>
> Ronnie Doggart
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