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From "Laura Stewart" <scotsmat...@gmail.com>
Subject Re: optimizer documentation
Date Mon, 12 Jun 2006 18:46:48 GMT
***(LS) Please post comments and responses to jira #"1397 Tuning Guide:
Puzzling optimizer documentation"

On 6/12/06, Laura Stewart <scotsmatrix@gmail.com> wrote:
>
> *** (LS) Sorry, accidently sent before I finished my list of questions
> :-)  See below.
>
>
> On 6/12/06, Laura Stewart <scotsmatrix@gmail.com> wrote:
>
> >  *** (LS) Rick - I can work on updating this text... questions below.
> >
> >  On 6/12/06, Satheesh Bandaram < bandaram@gmail.com> wrote:
> >
> > > Rick Hillegas wrote:
> >
> > > "If memory use is not a problem for your environment, set this
> > > property to a high number; allowing the optimizer the maximum
> > > flexibility in considering a join strategy queries involving large
> > > queries leads to better performance. It can also be set to smaller
> > > values for more limited environments."
> > >
> > > I can't find the name of this property on that page of the Tuning
> > > Guide. I'm also confused about what we consider to be a "high number"
> > > versus what we consider to be "smaller values". Would appreciate
> > > advice here.
> >
> > The property it may be referring to is
> > *derby.language.maxMemoryPerTable*. The default value is 1024 KB.
> >
> > Current default value is too small, so it would be a good tip for
> > developers to know and tune this property. It would be great if Derby
> > can configure this property value based on factors like max heap size,
> > size of data cache and/or other parameters.
> >
> > If you are opening a documentation bug for other issue you found, may be
> > you can include this omission as well.
> >
> > Satheesh
> >
> >  *** (LS) Questions
> >
>  - Are we sure that the name of the property is
> derby.language.maxMemoryPerTable ?
> -  What is the maximum value allowed?
>  - Is there a value that we want to recommend for users to specify?
> - The text says that it can be set to smaller values, what is the minimum
> value that we recommend?
>
> Laura Stewart
>



-- 
Laura Stewart

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