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Difference between awr metrics [message #404623]

Fri, 22 May 2009 08:44

orausern
Messages: 826
Registered: December 2005

Senior Member

Hi,

I am not clear on what is the difference between buffer Nowait% and buffer hit%. I think buffer no wait means a requested buffer is available without having to wait. and buffer hit means the reqeusted buffer is avaialle. so what is the difference in these two metrics?

Can someone explain it?

Thanks

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Re: Difference between awr metrics [message #404629 is a reply to message #404623]

Fri, 22 May 2009 09:18

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

Senior Member

Buffer Hit% is the ratio of blocks that were already in the buffer cache to the total number of blocks read - ie the more blocks need to be read in from disk, the lower this %age

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Re: Difference between awr metrics [message #404632 is a reply to message #404629]

Fri, 22 May 2009 09:29

orausern
Messages: 826
Registered: December 2005

Senior Member

Thank you, what I amnot clear is conceptually how is it different from buffer nowait%? Also can you explain what are the different types of buffers in oracle?

Thanks

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