Re: 7.3 schedule

Barry Lind wrote:
> Oracle's implementation is a shared cache for all plans.  This was 
> introduced in Oracle 6 or 7 (I don't remember which anymore).  The net 
> effect was that in general there was a significant performance 
> improvement with the shared cache.  However poorly written apps can now 
> bring the Oracle database to its knees because of the locking issues 
> associated with the shared cache.  For example if the most frequently 
> run sql statements are coded poorly (i.e. they don't use bind variables, 
> eg.  'select bar from foo where foobar = $1' vs. 'select bar from foo 
> where foobar =  || somevalue'  (where somevalue is likely to be 
> different on every call)) the shared cache doesn't help and its overhead 
> becomes significant.

This is very interesting.  We have always been concerned that shared
cache invalidation could cause more of a performance problem that the
shared cache gives benefit, and it sounds like you are saying exactly
that.

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