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Old 06-02-2006, 06:06 AM   #1
malru
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Logical vs Physical read


can anyone explain me,
what is logical read & physical read in terms of oracle?

And based on this how hit ratio is calculated in oracle?

Thanks,
Malru
 
Old 06-02-2006, 03:05 PM   #2
sundialsvcs
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If a read is satisfied without a physical I/O operation taking place, it is a logical read. A major purpose of the system is to maximize the percentage of such reads; that is, to maximize buffer effectiveness.
 
Old 06-02-2006, 03:24 PM   #3
J.W.
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Logical reads occur when the requested data exists in the buffer cache. If the requested data is not in the buffer, then the system needs to retrieve it from the hard drive, which is a physical read.
 
  


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