What is "hsqldb"

HSQLDB (Hyper Structured Query Language Database) is an open source database server (DBMS), written entirely in the Java language.

Main features:

• Basic SQL language support including junctions, triggers and views.
• Portability due to its implementation in Java.
• Repositories accessible through JDBC technology.
• Creation of databases in text file, database and in memory.
• Dump feature for easy backups.
• Takes up little disk space.
• Virtually no configuration required to operate.

Link to official page: Link