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From: satar@my-dejanews.com
Newsgroups: comp.databases.oracle.server
Subject: Re: db_block_buffers - can you have too many ? Thomas Kyte, please help!
Date: Thu, 12 Nov 1998 00:48:35 GMT
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I had a similiar experience, another DBA was evaluating my Database and told
me that I would have better performance if I lowered my db_block_buffers. I
couldn't understand the logic behind it, so I didn't do it. My cache hit
ratio is 99.97 percent, and I saw no tuning needs. I also wasn't paging or
swaping and everything is fine and dandy. My question is, why would anyone
suggest lowering the db_block_buffer parameter? My understanding was to shove
the whole database into the SGA whenever possible.

Satar

> > I had sudden performance problems - typical query
> > response times up by a factor of 10.  No change had been made to the box and
> > it's dedicated to Oracle.
> >
> > The database is quite large - 300 plus tables, and is heavily laden with
> > PLSQL code.
> >
> > With 256MB RAM on the box, I had increased db_block_buffers well above the
> > sample values shown in init.ora.  (but still keeping the SGA size well below
> > total RAM - total SGA size was approx 60MB)
> > Oracle support told me to reduce the db_block_buffers and this did actually
> > solve the problem !?
> >
> > Can anyone help me to explain this ?  Surely the more database blocks you
> > can cached, the better so long as your OS isn't swapping the SGA to disk ?
> > Or am I missing something.
>


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