Re: Range of values for buffer_gets in stats$sql_summary
- From: fairlie rego <fairlie_r@xxxxxxxxx>
- To: john.kanagaraj@xxxxxxxxx, vvardhineni@xxxxxxxxx
- Date: Tue, 28 Nov 2006 15:18:09 -0800 (PST)
Vijay,
As John mentioned the value is derived from v$sql which derives the value
from x$kglob and you have not mentioned the Oracle version.
Hence
if [ version -lt 10.1 ] ;
then bug=2758126
fi
Rediscovery information:
Query of v$sql or v$kglob could show negative values for disk_reads and
buffer_gets.
-Fairlie
John Kanagaraj <john.kanagaraj@xxxxxxxxx> wrote:
Vijay,
-ive values are generally due to wrap-around. Since STATSPACK data is just
snapshots of V$ views, which in turn are cumulative, you will see this issue
when your database has been up for a long time and the counter wraps around. In
the case of STATS$SQL_SUMMARY, the BUFFER_GETS is derived from
V$SQL.BUFFER_GETS. Negative values in buffer_gets may be seen in SQL that
results in a lot of buffer gets *AND* is 'kept alive' in the lib cache via
constant executions and pins. (I have one particular SQL that has this "issue"
on an Oracle Apps 11i instance)
What is the range of values for buffer_gets column in stats$sql_summary
table. Our tables have -ve values in few cases.
--
John Kanagaraj <><
DB Soft Inc
Phone: 408-970-7002 (W)
Disappointment is always inevitable; Discouragement is invariably optional
** The opinions and facts contained in this message are entirely mine and do
not reflect those of my employer or customers **
Fairlie Rego
Senior Oracle Consultant
http://www.linkedin.com/in/fairlierego
http://el-caro.blogspot.com/
M: +61 402 792 405
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