Re: dictionary cache

From: Howard J. Rogers <hjr_at_dizwell.com>
Date: Mon, 31 May 2004 20:59:52 +1000
Message-ID: <40bb101a$0$8985$afc38c87@news.optusnet.com.au>

"utkanbir" <hopehope_123_at_yahoo.com> wrote in message news:f6c90ebe.0405310232.2cd4b11b_at_posting.google.com...
> Hi everbody ,
>
> if i look at the sums ratio in v$rowcache , i have a very good
> disctionary cache get ratio, but if i look at individual entries , i see
low values for some
> objects such as dc_sequences:
> Is this a problem? According to the manual , individual misses should
> be less than <%2 , here it is %10???

No it's not a problem, because hit ratios are a complete waste of time anyway.

I hope you aren't diving in and tuning the dictionary cache first, by the way? Get the library cache right first, and the dictionary cache will always follow. And to get the library cache right, you look at things like library cache and shared pool latch contention rates. If you really must use ratios, then look at the library cache get/hit and reloads-to-pins ratio. If they are OK, then your dictionary cache will be fine (the point being is that Oracle's memory allocation algorithms favours the dictionary cache. So any memory shortages always show up in the library cache first).

Regards
HJR Received on Mon May 31 2004 - 05:59:52 CDT