Re: Buffer cache hit very low...!!!

On 9/13/05, Chirag DBA <chiragdba_at_gmail.com> wrote:
> This is the topic I have seen long long discussions but never ended up with
> a single voice.

There is no topic anywhere, about anything, that has a single voice. :)

>
> What I think is the main reason for performance is the bad SQLs and the next
> is index is not working properly. Might be because of getting split. Here we
> have lots of DMLs so might indexes are got split and are leading to FTS of
> the tables.
>

Rebuilding indexes leads to excessive block splits.

Please see http://www.actoug.org.au/Downloads/oracle_index_internals.pdf

Many of the things that you think to be true about Oracle are old myths (which may have contained a kernel of truth in very old versions of Oracle) which do nothing but cause you work.

You seem to be hitting a number of them. The most recent two:

• cache hit ratio must be maintained
• rebuild indexes to improve performance (rarely, but sometimes, is true)

Please concentrate on learning how Oracle works. Probably the single best book for that would be one of Tom Kyte's books.

He has a new one on the way (at the publishers?) so you may like to wait for that.

http://www.amazon.com/exec/obidos/search-handle-url/index%3Dbooks%26field-author-exact%3DThomas%20Kyte

-- 
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
11+ years of trying to appear to know what I'm doing.
--
http://www.freelists.org/webpage/oracle-l