Re: hit ratio

Pavel wrote:
>
> To all,
>
> I created a database with 400m of buffer cache on machine which have
> 2gig memory. This database is using CONTEXT option. The database is
> accessed by about 100 users at the time.
> The database seems to be performing all right but hit ratio is
> suggesting that I need more db_buffers (56%). It seems to me that
> 400meg should be more than enough.
> Any advice how to deal with this besides increasing db_block_buffers
> parameter?
>
> Thanks,
>
> Paul

You can query on x$kcbrbh to check the effectiveness of your database buffers. Method (of querying) is clearly mentioned in Oracle DBA manual: tuning memory. Its not always possible to achieve 90% and up cache hit, your application characateristics may be such. Since you are using CONTEXT option, I should think that yours is a text retrieval system or some such thing where its typical that large chunk of data may be retrieved but never be reused, in this case the hit ratio will be low. Also it depends on what point of time you are looking at the hit ratio. Hit ratio improves over the time, after the database start up, as more and more data is accessed.

Thanks. Received on Sat Aug 23 1997 - 00:00:00 CDT