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Home -> Community -> Mailing Lists -> Oracle-L -> RE: INSERT...SELECT pegs CPU, but is waiting on scattered read?
Yeah, I figured I'd need to post more info, but didn't want to scare away
folks (or clog their inboxes) with a 4MB trace. :)
Here's an expanded excerpt:
WAIT #26: nam='db file scattered read' ela= 3 p1=7 p2=35653 p3=8 WAIT #26: nam='db file scattered read' ela= 0 p1=7 p2=35661 p3=8 WAIT #26: nam='db file scattered read' ela= 1 p1=7 p2=35669 p3=8 WAIT #26: nam='db file scattered read' ela= 0 p1=7 p2=35677 p3=8 WAIT #26: nam='db file scattered read' ela= 0 p1=7 p2=35685 p3=8 WAIT #26: nam='db file scattered read' ela= 1 p1=7 p2=35693 p3=8...
TIMED_STATISTICS is on. I chose poorly on the example for the first post.
Here's the abbreviated explain plan:
SELECT STATEMENT Cost = 2364
2.1 NESTED LOOPS
3.1 TABLE ACCESS FULL QT_PART_HISTORY_24_MONTHS
3.2 TABLE ACCESS BY INDEX ROWID GLXREF
4.1 INDEX RANGE SCAN GLXREF_PRICELISTNO UNIQUE
I agree that what I *should* be seeing is ela's into the hundreds, but I'm
not. Each one of the "WAIT" lines above takes a couple of seconds or more
to pop into the trace file.
And, yes, we are using the infamous CS=F, which is causing the "SYS" bind names in the statement. One final piece that may be of importance, but I forgot to include on the original post is that each of these statements is dynamically generated and run via EXECUTE IMMEDIATE. There's no COMMIT between the EXECs, but I thought that it was implicit due to the nature of the EXECUTE command.
More thoughts?
Rich
Rich Jesse System/Database Administrator rich.jesse_at_quadtechworld.com QuadTech, Sussex, WI USA
> -----Original Message-----
> From: Daniel Fink [mailto:Daniel.Fink_at_Sun.COM]
> Sent: Thursday, April 29, 2004 12:13 PM
> To: oracle-l_at_freelists.org
> Subject: Re: INSERT...SELECT pegs CPU, but is waiting on
> scattered read?
>
>
> WAITs (or timed events) are emitted into the trace file upon
> completion. So the
> db file scattered read has completed (with an elapsed time of
> 0, which makes me
> wonder if timed_statistics is turned on). The logical next
> step is that the data
> returned by the scattered read (8 blocks worth) is processed.
> Probably logical
> i/os, sorting, hash joins, etc. all CPU intensive. Once the
> processing is
> completed, another physical i/o call is made and the process
> repeats. If the
> between i/o processing is the real problem, you will see the
> waits separated by
> seconds or minutes.
-- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------Received on Thu Apr 29 2004 - 13:09:38 CDT
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