Derby on embedded systems

[Joseph Monti <mo...@smartrobots.com>]

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

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[ Joseph Monti                            ___ ___ _ _     ]
[ Software Engineer                      / __| _ \ | |    ]
[ Smart Robots, Inc                      \__ \   /_  _|   ]
[ monti@smartrobots.com                  |___/_|_\ |_|    ]
[ http://www.smartrobots.com/                             ]
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Re: Derby on embedded systems

[Stanley Bradbury <br...@Mutagen.Net>]

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.