Re: Buffer Cache performance

Julio,

We had a problem with a big table which was set to "cache" and not "nocache", taking over the buffers, or at least a lot of them, whenever it was scanned. Increasing the value of db_block_buffers brought little increase in hit rate because of this. So it might be worth having a look to see if you've got any big cached tables. Just a thought.

Regards,
Terry.
Julio Gosmaalho <jgosmaalho_at_yahoo.com> wrote in message news:7vhi89$38c$1_at_duke.telepac.pt...
> Hi guys.
>
> In a Oracle 7.3 DB because of its slow performance i ran several scripts
and
> I found that the buffer hit ratio is the worst value ( about 50%). All the
> other values ,redo, rollback segment, latch contention data dictionary,
etc
> were ok (except library cache that needs a little adjustment - I
think...).
>
> So I increased the init.ora parameter from 200 DB_BLOCK_BUFFERS from 200
to
> 30.000, gradually - the memory of the NT Server allows that.
>
> RESULT - I only saw a benefit of 3% on the eficiency of the Buffer Cache
> !!!!!!!
>
> Is true that if the applications use full table scans, the buffer cache
isnt
> used ?
>
> The strange thing is that in another site we have the same applications,
> same machine, with the same database and now the same parameters and the
> performance is good.
>
> Do you have any idea about it ??
>
> TIA
>
> CC
>
>
Received on Sun Oct 31 1999 - 12:02:39 CST