Re: Questionable V$SQLAREA Statistics

Hi,

You should not compare tkprof outputs with V$SQL,V$SQLAREA. Because, recursive/child statistics are included in their parent statements in these views. But, tkprof substructs recursive statistics. I mean tkprof reports real values for statements, but dictionary doesn't.

regards...

"Orr, Steve" wrote:

> Here's the scene:
>
> 1) I have a 400,000 row table table which is cached.
>
> 2) I have a query against that table and no other with one column referenced
> in the WHERE clause. (This column is indexed and of course I don't really
> need the index since the table is cached but it's there so ho hum...)
>
> 3) When I run tkprof on the query it shows a full table scan ignoring the
> index... that's what I want 'cause it's cached.
>
> 4) But when I look at V$SQLAREA the DISK_READS column is incremented.
>
> 5) This query is executed very often so my StatsPack report lists it as one
> of the most expensive queries in terms of physical reads.
>
> It appears that Oracle is counting full table scans of cached tables as
> DISK_READS in V$SQLAREA. Seems like this is a bug to me 'cause it's not
> really a physical disk read but is getting data from the buffers.
>
> Don't you think this is a bug? Has anyone seen this before?
>
> Steve Orr
> Looking for cache in Bozeman, Montana
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--
Danisment Gazi Unal
http://www.ubTools.com


-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Danisment Gazi Unal (ubTools)
  INET: dunal_at_ubTools.com

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