Dear Antonio,

you do not mention what OS you run your Derby on but in case you are on Unix they provide workaround to your requested feature already. For example by default on all Solaris you have /tmp mounted as tmpfs in swap which is in memory.

Hopefully this helps to you or others.


On Tue, Sep 16, 2008 at 10:47 AM, Antonio Goncalves <> wrote:

I'm using the Derby network database to run my application and the Embedded mode for testing. Both work fine. But when I use the Embedded mode, Derby creates a directory on my hard drive full or files. I would like just to have a in-memory database, no I/O, just in-memory. Is it possible with Derby ?  This is what I have at the moment :

<persistence-unit name="jolorunSampleJpaPU">
            <property name="eclipselink.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver"/>
            <property name="eclipselink.jdbc.url" value="jdbc:derby:myDB;create=true" />
            <property name="eclipselink.jdbc.user" value="APP" />
            <property name="eclipselink.jdbc.password" value="APP" />
            <property name="eclipselink.ddl-generation" value="drop-and-create-tables" />

I've seen a very old thread ( that mentions the URL jdbc:derby:memory:myDb but that doesn't work. I've cheked out the Derby source code but didn't find anything about that.

Any idea ?