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Home -> Community -> Mailing Lists -> Oracle-L -> RE: buffer cache
I'm ready for Jonathon's next book.
Along those lines, I think Amazon is going to start charging me for
frequent searches to see if your book is available for pre-order yet.
>>> cary.millsap_at_hotsos.com 05/08/03 11:52AM >>>
High BCHR is not *necessarily* bad, as Zhu Chao says. But, a systemwide
BCHR
in excess of 95% or so is often an indication of one or more
inefficiencies
that can result in greatly improved performance if corrected:
For more information, see my "Why a 99% buffer cache hit ratio is *not*
ok",
and perhaps Jonathan will tell you how to access his "The database
gets
better but the metrics look worse" article that he presented at IOUG.
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- Hotsos Clinic 101 in London, Reykjavik, Ottawa, Dallas, Washington,
Denver, Sydney
- Visit www.hotsos.com for schedule details...
-----Original Message-----
Sent: Thursday, May 08, 2003 3:32 AM
To: Multiple recipients of list ORACLE-L
Hi,stephane,
Though BCHR tuning method is widely critiqued, high buffer cache
hit
ratio is not necessary bad either, right?
Maybe high cache hit ration and v$bh with a lot of free/cr block
means
too big data buffer.
Here is an example of too big data buffer:
15:29:44 SQL> select /*+rule*/ status,count(*) from v$bh group by status;
STATU COUNT(*)
----- ----------
cr 55120 free 54656 scur 17696 xcur 24549
4 rows selected.
Elapsed: 00:00:01.32
While in another database with large sga,I think this buffer cache
is
not too big:
15:27:05 perfstat_at_BIDDB.EACHNET.COM> select /*+rule*/ status,count(*)
from
v$bh group by status;
STAT COUNT(*)
cr 11162
read 1
xcur 1037413
Regards
zhu chao
msn:chao_ping_at_163.com
www.cnoug.org(China Oracle User Group)
----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
Sent: Monday, May 05, 2003 7:11 PM
> High BCHR, V$BH ...
>
> >----- ------- Original Message ------- -----
> >From: Arvind Kumar <arvindk_at_sqlstarintl.com>
> >To: Multiple recipients of list ORACLE-L
> ><ORACLE-L_at_fatcity.com>
> >Sent: Mon, 05 May 2003 02:41:36
> >
> >Dear All,
> >
> > how can i check if my buffer cache is bigger
> >than necessary ?oracle db
> >version is 8.1.7.
> >
> >
> >Thanks
> >
> >
> >Arvind
> >
> >
> >--
> >Please see the official ORACLE-L FAQ:
> >http://www.orafaq.net
> >--
> >Author: Arvind Kumar
> > INET: arvindk_at_sqlstarintl.com
> >
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> >------------------
>
> Regards,
>
> Stephane Faroult
> Oriole
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Stephane Faroult
> INET: sfaroult_at_oriolecorp.com
>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: zhu chao INET: chao_ping_at_vip.163.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Cary Millsap INET: cary.millsap_at_hotsos.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Darrell Landrum INET: DLANDRUM_at_zalecorp.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu May 08 2003 - 13:14:58 CDT
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