OraFAQ Forum: Performance Tuning » Buffer pool Hit% more than 100%

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Buffer pool Hit% more than 100% [message #431182]

Mon, 16 November 2009 01:19

DBA_SangramKeshari
Messages: 44
Registered: October 2009
Location: Mumbai

Member

In one of my AWR Report under tab Instance Efficiency Percentages (Target 100%) , My Buffer Hit % is showing as 102.01 .

I am not able to understand how can this possible to more than 100%.

Please revert.

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Re: Buffer pool Hit% more than 100% [message #431194 is a reply to message #431182]

Mon, 16 November 2009 02:25

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

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Because the formula is wrong.

Regards
Michel

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Re: Buffer pool Hit% more than 100% [message #431328 is a reply to message #431194]

Mon, 16 November 2009 19:29

DBA_SangramKeshari
Messages: 44
Registered: October 2009
Location: Mumbai

Member

How the formula is wrong.?
Do you mean to say the way oracle is calculating the % is wrong.?

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Re: Buffer pool Hit% more than 100% [message #431339 is a reply to message #431328]

Mon, 16 November 2009 23:11

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
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Quote:

How the formula is wrong.?

In the way it returns more than 100%.

Regards
Michel

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Re: Buffer pool Hit% more than 100% [message #431371 is a reply to message #431182]

Tue, 17 November 2009 03:29

DBA_SangramKeshari
Messages: 44
Registered: October 2009
Location: Mumbai

Member

There must be some logic that it is coming more than 100.
It cann't be possible that oracle is calculating it in a wrongway.

Are you saying it's a oracle BUG?

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Re: Buffer pool Hit% more than 100% [message #431394 is a reply to message #431371]

Tue, 17 November 2009 04:02

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
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Quote:

It cann't be possible that oracle is calculating it in a wrongway.

This is the best one in this day.

Quote:

Are you saying it's a oracle BUG?

It looks like it is.

Regards
Michel

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Re: Buffer pool Hit% more than 100% [message #434112 is a reply to message #431394]

Mon, 07 December 2009 03:59

DBA_SangramKeshari
Messages: 44
Registered: October 2009
Location: Mumbai

Member

I guess you must have tested it before replying me back.
Is that correct Mr M.???

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Re: Buffer pool Hit% more than 100% [message #434117 is a reply to message #434112]

Mon, 07 December 2009 04:06

Michel Cadot
Messages: 68653
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Useless to test something that is obviously wrong just like a likelyhood greater than 1.

Regards
Michel

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Re: Buffer pool Hit% more than 100% [message #434152 is a reply to message #434112]

Mon, 07 December 2009 08:21

JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...

Senior Member

Why do you have such difficulty believing that something that Oracle ships could have a bug in it.

They're far from the worst offender in the IT industry, but some of the software they've shipped (Oracle DB v 10.1 for example) contained a noticable number of bugs.

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Re: Buffer pool Hit% more than 100% [message #434222 is a reply to message #431182]

Mon, 07 December 2009 19:59

DBA_SangramKeshari
Messages: 44
Registered: October 2009
Location: Mumbai

Member

But we are using 10.2.0.4. Are you saying this also contains some bugs.?

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Re: Buffer pool Hit% more than 100% [message #434223 is a reply to message #434222]

Mon, 07 December 2009 20:08

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

> Are you saying this also contains some bugs.?
Check out the fixed BUG List published with V11!

[Updated on: Mon, 07 December 2009 20:09]

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Re: Buffer pool Hit% more than 100% [message #434224 is a reply to message #431182]

Mon, 07 December 2009 20:11

DBA_SangramKeshari
Messages: 44
Registered: October 2009
Location: Mumbai

Member

Where to check.?

[Updated on: Mon, 07 December 2009 20:33] by Moderator

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Re: Buffer pool Hit% more than 100% [message #434225 is a reply to message #434224]

Mon, 07 December 2009 20:33

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

Comes with product download

On my system is URL for known V10.2.0.4 bugs

file:///u01/app/downloads/database/doc/readmes.102/b14233/toc.htm#CHDDJCFH

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Re: Buffer pool Hit% more than 100% [message #434246 is a reply to message #434222]

Tue, 08 December 2009 02:20

JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...

Senior Member

Quote:

But we are using 10.2.0.4. Are you saying this also contains some bugs.?

Yes

Think about this - your AWR report says that of all the blocks read, 102.01% of them came from the buffer cache.

This number cannot be correct. The script must be ignoring some set of blocks, or counting some blocks twice, or some similar error - what the exact error is doesn't affect the fact that in order to get that value there has to be an error in the calculation.

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