light weight in memory database with the option of saving to csv/xml files

Hi

I am looking for a light weight in memory Java database that will have the option of saving tables and loading it from disc too.

I am looking for a database that can run as a part of my application and not as a separate process. It should be able to compute selection, projection and joins efficiently.

Please advice me about this. The database will be used as a part of my java application.

Regards
Swaroop

Have you looked at HSQLDB?

that's what I was going to say.

Thanks a lot. I saw it and a few others on the web but needed some advice to trust this. I see that its good and supports both in memory tables and tables in simple csv files.

How about SQLite. I read about this and see that this is also widely used for the same purpose. Its used by a lot of Google products too like Google gears.

Regards
Swaroop

Hypersonic (as mentioned above)

H2 - http://www.h2database.com/html/main.html

Derby - http://db.apache.org/derby/

If you are likely to have concurrent requests, or often re-sorting fields, use Derby: http://dhartford.blogspot.com/2010/01/embedded-db-sort-stability-pagination.html

Thanks a lot Darren. I think Derby will suit me best.

SQLite has a JDBC driver, but is written in C, not Java.

Yeah I saw that. Thanks Ulf.

Swaroop