http://www.justingordon.org/2008/10/in-memory-dbs-for-tdd-h2-versus-hsqldb.html
It is relatively simple to switch between them. Mostly, it's a matter of switching the JDBC connection string.


http://www.encorewiki.org/display/encore/Open+Source+Databases+Comparison

http://stackoverflow.com/questions/2746201/which-is-better-h2-or-hsqldb
HSQLDB highly outperforms H2 in DDL operations as well as when starting/shutting down the instance, even for a small database.


http://3rdstage.blogspot.com/2009/03/comparion-of-hsqldb-h2-sqlite.html
http://database-management-systems.findthebest.com/compare/6-15-16/Apache-Derby-vs-HSQLDB-vs-H2


http://www.h2database.com/html/faq.html
running out of memory should be avoided. In older versions, OutOfMemory errors while using the database could corrupt a databases.



try ozeki in berghie's pc


tomorow:
create Common module
move common package to Common module



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