What is "hsqldb"

HSQLDB (Hyper SQL Database) is a relational database management system written in Java. It has a JDBC driver and supports a large subset of SQL-92 and SQL:2008 standards. It offers a fast, small (around 1300 kilobytes in version 2.2) database engine which offers both in-memory and disk-based tables. Both embedded and server modes are available for purchase.

Additionally, it includes tools such as a minimal Web server, command line and GUI management tools (can be run as applets), and a number of demonstration examples. It can run on Java runtimes from version 1.1 upwards, including free Java implementations such as Kaffe.

HSQLDB is available under a BSD license. It is used as a database and persistence engine in many open source software projects, such as OpenOffice Base, LibreOffice Base, the Standalone Roller Demo, and the Jitsi VoIP and video-conference client since version 2.6. It is also used in commercial products, such as Mathematica and InstallAnywhere (starting with version 8.0).