I was looking at derby and the FAQ says in Memory version has not been completed, but to check with list..  It also said this about six months ago :)  Just wondering if anything is being done on it...
 
Seems that derby in my environment takes about 3 times as long as HSQL to startup and import my starting data, and I assume this is due to difference in mem/disk operations.   Oddly derby is WAY faster on all join queries than hsql, so I was really hoping to use it.
 
Thanks!