high db hit ratio and a lot of waits on db sequential reads

From: genegurevich@xxxxxxxxxxxx
To: oracle-l <oracle-l@xxxxxxxxxxxxx>
Date: Tue, 25 Sep 2007 13:57:08 -0500

Hi all:

I am working on tuning an app running against oracle 10.2.0.3 We have 48G
on the server; my db_cache is 18G. When I
look at the awr reports, I see db hit ratio being over 99% and a lot of
waits for db sequential reads. Based on the SQL
there are a lot of table reads based on the primary keys so that kind of
waits is reasonable. But the question is
if the hit ratio is that high , if we read mostly for the cache, why do we
do that many reads. Is there an explanation for that?

thank you

Gene Gurevich


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Follow-Ups:

RE: high db hit ratio and a lot of waits on db sequential reads
From: Bobak, Mark

Re: high db hit ratio and a lot of waits on db sequential reads
From: Andrey Kriushin

Re: high db hit ratio and a lot of waits on db sequential reads
From: LS Cheng

Re: high db hit ratio and a lot of waits on db sequential reads
From: Terry Sutton

high db hit ratio and a lot of waits on db sequential reads

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