I am considering to use one of these DB.

Java DB comes with Java 6 and it is big plus.

I plan to use it in desktop app and I wish to be able to upload a lot of data.

I made a test on PC with 1 GB of memory.

Both database started to work (SELECT/INSERT) when DB grown bigger then 768MB.
It seems that these DBs work well when data is in memory.

While MySQL was more stable when DB was bigger then available memory.

May be I made a wrong test.

Could you advise what DB is better or what pitfalls do they have?