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From Stanley Bradbury <bradb...@Mutagen.Net>
Subject Re: Derby on embedded systems
Date Thu, 25 Nov 2004 01:45:53 GMT
Joseph Monti wrote:

>Hi,
>
>I am wondering if anyone has any advice on running Derby on embedded
>hardware. I'm not referring to the embedded database engine, but running
>it on a constrained system. 
>
>The target system is a 60Mhz ARM7 with 32MB RAM and 128MB persistent
>memory. Our primary language is Java and we were intrigued by the
>capabilities and the whole idea of Derby so we are beginning to consider
>it as our primary database.
>
>We are currently using MySQL (Don't ask how, it wasn't easy) and are
>looking for other options.
>
>Should we even bother?
>
>Are there any properties/settings to which we should be paying close
>attention?
>
>Thank you!
> - Joe Monti
>
>  
>

Hi Joe -

I have no experience with ARM7 but can tell you that the key to using 
Derby in any environment is the features supported by the JVM.  Derby 
requires a full featured JVM (J2SE), some of the JVMs written for small 
devices do not support all functions needed (J2ME).  I suspect that much 
of the 32Mb RAM will need to be allocated to the JVM but that is just a 
guess. 

You would need to configure Derby to it's smallest reasonable size - 
look carefully at the configuration parameters in the documentation - 
the main one is pageCacheSize:
 derby.storage.pageCacheSize  - default = 1000 pages     minimum value =  40

Another that could help with persistant storage is:
derby.storage.pageReservedSpace <perf86.htm#sii-proper-28026>

Hope this helps.




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