Re: Large DB buffer, low cache hit ratio

What happens here is
badly tuned application
absence of proper indexes
no statement tuned
probably aged statistics
etc, etc, etc
In 80 percent of all cases a badly performing application is not the result of a badly tuned database, it is a result of badly written app. If you have that number of db_block_buffers (which is in violation of Oracle's recommendation of a max SGA of one third of physical mem) and you still have a hitrate of 24 percent, rest assured it is the app.

Hth,

Sybrand Bakker, Oracle DBA

<yunhuiyang_at_my-deja.com> wrote in message news:94ib6g$cgj$1_at_nnrp1.deja.com...
> Hi, all,
>
> The OS has 1G mem. SGA is about 700M, DB_BLOCK_BUFFERS is about 500M
> (133230*4K) in bytes. The size of whole database data files is less
> than 50G. So the DB_BLOCK_BUFFERS is more than 1% of the total database
> size. While the database buffer cache hit ratio only 24%. Please advice
> what happens here.
>
> Thank you.
>
> Helen
>
>
> Sent via Deja.com
> http://www.deja.com/
Received on Mon Jan 22 2001 - 17:22:49 CST