Hi, Carel-Jan and Rich,
Connor's script to bump up buffer cache hit ratios is meant to be a humor. Only
if you carefully comtemplate it will you see that there's no relevance of the
fact that you can get any hit ratio to the fact that hit ratios are
insufficient in performance tuning.
It would
Yong,
Connor's script is not a joke, it's a proof by counterexample that the
advice You SQL is tuned if and only if it has a high hit ratio is
rubbish.
The buffer cache hit ratio is a tool. Used properly, nobody's objecting.
It's proper use? To answer the question, What percentage of LIO calls
Yong:
I have not seen all the threads on this. So there are chances some body
might have
covered this/I may be missing some interesting things..But the issue is,
tuning or measuring the
database performance ONLY with Hit Ratios. By high hit ratios Damagement
will tend to understand , that
are there really that many people who use hit ratio?
From: Cary Millsap [EMAIL PROTECTED]
Date: 2003/12/23 Tue AM 11:49:33 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: RE: Hit Ratio
Yong,
Connor's script is not a joke, it's a proof by counterexample
]
Subject: RE: Hit Ratio
Yong,
Connor's script is not a joke, it's a proof by counterexample that the
advice You SQL is tuned if and only if it has a high hit ratio is
rubbish.
The buffer cache hit ratio is a tool. Used properly, nobody's
objecting.
It's proper use? To answer
of list ORACLE-L
are there really that many people who use hit ratio?
From: Cary Millsap [EMAIL PROTECTED]
Date: 2003/12/23 Tue AM 11:49:33 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: RE: Hit Ratio
Yong,
Connor's script is not a joke, it's a proof
, December 23, 2003 12:29 PM
To: Multiple recipients of list ORACLE-L
are there really that many people who use hit ratio?
From: Cary Millsap [EMAIL PROTECTED]
Date: 2003/12/23 Tue AM 11:49:33 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: RE: Hit Ratio
of list ORACLE-L
Cc:
Subject:RE: Hit Ratio
Yong,
Connor's script is not a joke, it's a proof by counterexample that the
advice You SQL is tuned if and only if it has a high hit ratio is
rubbish.
The buffer cache hit ratio is a tool. Used properly, nobody's objecting.
It's proper use
At 12:04 23-12-03 -0800, you wrote:
Jared,
I'm going to take some exception to what Cary has said on the
subject, but I believe in the end she'll agree with me.
She? Cary, you didn't tell us about this surgery ;-)
Dick, last time I saw Cary (October) he was very masculin. I bet this
SORRY!! Regrettably e-mail does not provide the required info, namely a picture. The
only other Cary I know is female, in every sense of the word.
Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA
-Original Message-
Sent: Tuesday, December 23, 2003 3:45 PM
To: Multiple recipients
of list ORACLE-L [EMAIL PROTECTED]
Subject: RE: Hit Ratio
Yong,
Connor's script is not a joke, it's a proof by counterexample that the
advice You SQL is tuned if and only if it has a high hit ratio is
rubbish.
The buffer cache hit ratio is a tool. Used properly, nobody's
objecting
Why do people still talk about THE
buffer cache hit ratio ? There are lots
of them.
The one you can get from v$sysstat,
the ones you can get from v$buffer_pool_statistics,
and the ones you can get from v$segstat.
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The educated person is
Exactly.
select * from v$statname where name like '%gets%'
is simple evidence of that.
Cheers
Connor
--- Jonathan Lewis [EMAIL PROTECTED]
wrote:
Why do people still talk about THE
buffer cache hit ratio ? There are lots
of them.
The one you can get from v$sysstat,
the ones you can
Well, I guess I could have added a :) after my request on how
to fix the hit ratio, but it wouldn't be nearly as much fun.
On Sun, 2003-12-21 at 03:29, Mogens Nrgaard wrote:
Ah yes, you could introduce heuristically (spelling?!) skewed hit
ratios. As Dave Ensor explained at UKOUG, the word
As a friendly reminder, when debunking myths, I suggest we keep sober and never
go overboard. The recently popular formula to get an arbitrary hit ratio is not
what a database in normal usage naturally gets. Unless a mischievous developer
plays a prank, hit ratios are still useful to some extent
My BCHR is currently 96.62%. In the past, it was normally over 99%. What
should I do?
I'll be waiting for Mladen's reply... :)
Rich
Rich Jesse System/Database Administrator
[EMAIL PROTECTED] Quad/Tech Inc, Sussex, WI USA
-Original
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: RE: Hit Ratio
My BCHR is currently 96.62%. In the past, it was normally over 99%. What
should I do?
I'll be waiting for Mladen's reply... :)
Rich
Rich Jesse System/Database Administrator
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: RE: Hit Ratio
My BCHR is currently 96.62%. In the past, it was normally over 99%. What
should I do?
I'll be waiting for Mladen's reply... :)
Rich
Rich Jesse System/Database Administrator
[EMAIL
At 11:14 22-12-03 -0800, you wrote:
My BCHR is currently 96.62%. In the past, it was normally over 99%. What
should I do?
I'll be waiting for Mladen's reply... :)
Rich
Rich Jesse System/Database Administrator
[EMAIL PROTECTED] Quad/Tech Inc, Sussex,
PROTECTED]
Date: 2003/12/22 Mon PM 02:14:26 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: RE: Hit Ratio
My BCHR is currently 96.62%. In the past, it was normally over 99%. What
should I do?
I'll be waiting for Mladen's reply... :)
Rich
--
Please see the official
Rich,
you mean due to 'no change mode' you can't even change your hit ratio ... too bad.
Happy holidays everyone !!
Raj
Rajendra dot Jamadagni at nospamespn dot com
All Views expressed in this email are strictly
Easy,
A new formula for the hit ratio
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The educated person is not the person
who can answer the questions, but the
person who can question the answers -- T. Schick Jr
One-day tutorials:
http://www.jlcomp.demon.co.uk/tutorial.html
- Original Message -
Actually, it isn't SAP. I was simply creating a set of MV's
based on SAP tables in another database.
Fair enough.
I wonder what I need to tune to fix this?
stop creating those tables?
D
Seriously: aren't you getting the I/O as mostly writes during the
Ah yes, you could introduce heuristically (spelling?!) skewed hit
ratios. As Dave Ensor explained at UKOUG, the word heuristic in
Oracle's optimizer code can be translated directly into constant. So
add a number here or there until it fits.
Mogens
Jonathan Lewis wrote:
Easy,
A new formula
¦D
Unreal, eh? that's SAP for you...
Cheers
Nuno Souto
[EMAIL PROTECTED]
- Original Message -
Just thought I would share my hit ratio with y'all.
--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Nuno Souto
INET: [EMAIL PROTECTED]
Fat City Network
Actually, it isn't SAP. I was simply creating a set of MV's
based on SAP tables in another database.
The script I was running is used to keep track of how much
IO is going on, just to ensure that everything is still
working during the build. Once the physical IO exceeds
the logical IO, the HR
Set up a dbms_job to run the command select 'x' from dual; every 10
seconds or so. I think you'll find that your hit ratio increases quite
nicely.
Oh, the only potential downside is that your overall system performance
might go down, way down! But your ratios are great!
It is kind of like taking
Why do care about this? Are people complaining?
Anjo.
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Tuesday, November 19, 2002 8:04 PM
Hi
One of my database showing hit ratio low (=75% approx).I increased the
parameters.After last reboot
What problem? Seriously, the buffer cache hit ratio is a pretty meaningless
value (for details on why, see Cary Millsap's papers on www.hotsos.com).
Are your users complaining? Are you seeing behavior on the system (disk
contention, etc.) that makes you expect that your users will be complaining
With Connor McDonald's script in the DBA tool kit, no one should be complaining about
a bad BCHR. Ever :)
;-)
Get the script from his web site : http://www.oracledba.co.uk/
- Kirti
-Original Message-
Sent: Tuesday, November 19, 2002 3:24 PM
To: Multiple recipients of list
How about hiring a consultant?
-Original Message-
Sent: Thursday, February 08, 2001 4:41 PM
To: Multiple recipients of list ORACLE-L
It had only been up for a few weeks. It could be the buffer cache.
-Original Message-
mailto:[EMAIL PROTECTED] ]
Sent: Thursday,
If I were you I would check whether anything went wrong with the parameter file while recovering from the crash. MAke sure Pramter settings are as is before the crash.
Check your indexes, trigeers.
Check whether the packages and procedures are pinned as they were before crash.
These are few of
Title: Hit Ratio fallen through the floor at 31% since a db crash yesterday
I tried that one already!!
-Original Message-From: Kimberly Smith
[mailto:[EMAIL PROTECTED]]Sent: Thursday, February 08,
2001 12:19 PMTo: Multiple recipients of list
ORACLE-LSubject: RE: Hit Ratio
Title: Hit Ratio fallen through the floor at 31% since a db crash yesterday
Checkforlostorinvalidindexes
-Original Message-From: Barbra Hale
[mailto:[EMAIL PROTECTED]]Sent: Thursday, February 08, 2001
12:02 PMTo: Multiple recipients of list ORACLE-LSubject:
Hit Ratio fallen
Just wondering...how long was the instance up before the crash?
Could it be that your buffer cache just hasn't built up to where it was
before the crash?
Rich Jesse System/Database Administrator
[EMAIL PROTECTED] Quad/Tech International, Sussex, WI USA
Barb, pick the slowest application and examine it for the waits. What is the
application waiting for?
Take a look at v$session_event (cumulative) and v$session_wait (current
wait). If you see things
like "scattered db file read' or 'sequential db file read', then you have a
problem with access
Title: RE: Hit Ratio fallen through the floor at 31% since a db crash ye
It had only been up for a few weeks. It could be the buffer cache.
-Original Message-
From: Jesse, Rich [mailto:[EMAIL PROTECTED]]
Sent: Thursday, February 08, 2001 1:03 PM
To: Multiple recipients of list
37 matches
Mail list logo
