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From Knut Anders Hatlen <knut.hat...@oracle.com>
Subject Re: Cache Hit/Miss rates for Derby pageCache
Date Fri, 18 May 2012 14:20:12 GMT
Mike Matrigali <mikem_app@sbcglobal.net> writes:

> On 5/17/2012 10:07 AM, David Zanter wrote:
>> Does anyone know, is there a way to get derby statistics from a
>> running system regarding the hit/miss rates for the Derby Page Cache.
>> i.e.  Statistics that would help determine if the:
>> derby.storage.pageCacheSize  was being effective or needs to be
>> tweaked.
>> ~David
> cloudscape use to have this functionality, but I don't think it was
> exposed in derby as it depended on non-standard vti's.  Does anyone
> know if the jmx work provided this functionality.

I don't think the JMX work exposed any statistics from the engine.
Another problem is that we only collect statistics in Clock, whereas
ConcurrentCache, which is the cache implementation we use on Java 5 and
newer, does not collect any statistics currently.

It would be useful functionality, so it's probably worth filing a JIRA
issue for it.

Knut Anders

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