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RE: buffer cache

From: Cary Millsap <cary.millsap_at_hotsos.com>
Date: Thu, 08 May 2003 11:12:50 -0800
Message-ID: <F001.00594409.20030508111250@fatcity.com>


:)

Mine should be available for purchase in July. I'll be finishing up within the next couple of weeks.

I'm waiting for Jonathan's next book too. The more encouragement he gets from everyone, the more likely he'll consider taking it on as a project.

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-----
Landrum
Sent: Thursday, May 08, 2003 1:15 PM
To: Multiple recipients of list ORACLE-L

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 
> >
> >Fat City Network Services    -- 858-538-5051
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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 

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Author: Cary Millsap
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Author: Cary Millsap
  INET: cary.millsap_at_hotsos.com

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Received on Thu May 08 2003 - 14:12:50 CDT

Original text of this message

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