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From "Hiram Chirino" <hi...@hiramchirino.com>
Subject Re: Running 2 Derby instances on 1 JVM, do system properties cut it??
Date Wed, 22 Mar 2006 19:26:17 GMT
Hi Matt,

That sounds like it's worth a try.  Got an example of how to use
absolute database names?

Regards,
Hiram

On 3/22/06, Matt Sanford <mzsanford@aol.com> wrote:
> Hello,
>
>     I currently use two separate databases from within the same JVM by
> specifying absolute database names (rather than derby.system.home and a
> relative path). This keeps my files separated and seems to work very
> well. Is there some monitor locking within Derby that is essentially
> synchronizing these under the covers ? I have seen a performance
> improvement so I suspect that if there is it is minimal.
>     In my case I found much of my time was spent waiting on my static DB
> class. To fix it I open multiple databases and choose them using a hash
> of one of my key fields. works like a charm.
>
> Cheers;
>   -- Matt Sanford
>
> David.Vancouvering@Sun.COM wrote:
> > Hi, Hiram.  You have hit on an issue that prevents multiple databases
> > from being run within the same VM.  This is something we want to fix
> > in Derby, but it's a fairly big effort.
> >
> > As it stands the only way to configure the Derby database home is with
> > system properties.  So all uses of Derby within a given VM must access
> > the same database home and use the same system-wide configuration.
> >
> > David
> >
> > Hiram Chirino wrote:
> >> Hi Everybody,
> >>
> >> ActiveMQ makes extensive use of Derby for storage of it's persistent
> >> messages.  You have have done a great job with Derby!  Thanks for the
> >> hard work!
> >>
> >> One of the things that ActiveMQ supports is running multiple brokers
> >> on 1 JVM.  In that case we would actually like to run 2 derby
> >> instances with different data directories.  It seems that currently we
> >> have to set the "derby.system.home" to configure where the data files
> >> should go.  This does not seem to lend itself to supporting multiple
> >> derby instances with each with it's own data directory.  Is it
> >> possible to fully configure derby without using System properties??
> >>
> >> --
> >> Regards,
> >> Hiram
>
> --
>
>
> We love flattery, even though we are not deceived by it,
> because it shows that we are of importance enough
> to be courted.
>
>     -Ralph Waldo Emerson, writer and philosopher (1803-1882)
>
>


--
Regards,
Hiram

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