Re: library cache hit ratio > 100%

James Howerton wrote:

>DBA's,
>
>Has anyone seen library cache hit ratio > 100% ??? This is a very busy
>production database, it is usually < 97 % ( I don't tune by hit ratios
>I'm just curious).
>
>
>SQL> select SUM(PINS)/(SUM(PINS)+SUM(RELOADS))*100
> from v$librarycache;
>
>
>Library Hit Ratio
>--------------------------
> 100.009799
>
>1 row selected.
>
>
>

This is a well known bug from 8i: all quantities in X$ tables are 32-bit and when the database is
busy enough, those quantities can turn negative. That is how you get negative reloads. That was
limiting usefulness of statspack on 8i, too.Don't worry, be happy, you're living in the database tuner's
paradise: BCHR>100%. What else can you ask for?

-- 
Mladen Gogala
Oracle DBA
Ext. 121


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