Re: Another Oracle "Myth"?

From: Noel <tbal_at_go2.pl>
Date: 21 Nov 2003 01:41:09 -0800
Message-ID: <ec30e927.0311210141.3369e057@posting.google.com>

"Anurag Varma" <avdbi_at_hotmail.com> wrote in message news:<yDfvb.529$Sm1.65_at_news02.roc.ny>...
> "Geomancer" <pharfromhome_at_hotmail.com> wrote in message news:cf90fb89.0311201853.126b1516_at_posting.google.com...
>
> He does not say that 99.9% hit ratio is always bad (which you seem to be interpreting).
> However he does seem to be saying one should NOT rely on 99.9% hit ratio to make the judgment that
> the database performance is good. The fact might just be the opposite.

Not hard to imagine bad sql query slowing the database performance. Hit ratio hides number of memory/disk reads. If you would load all datafiles into memory and database buffers the hit ratio would always be 100%.
In that case, relying on hit ratio you would never find what slow your database, saying 'My database is perfect, no disk reads at all'.

If you multiple that hit ratio by number of reads you find bad sql query.

You should never rely on something what gives results as '%' :-)

> Did I say its an excellent article!

Yes, it is.

/Noel Received on Fri Nov 21 2003 - 03:41:09 CST