HSQLDB (Hyper SQL Database) is a relational database management system written in Java.
Multi-version Concurrency Control (MVCC) Two-Phase Locking (Deadlock Detection)
Relational
B+Tree
Physical Logging
Tuple-at-a-Time Model
SQL
Disk-oriented In-Memory
N-ary Storage Model (Row/Record)
Heaps
Embedded
http://hsqldb.org/
https://sourceforge.net/projects/hsqldb/
http://hsqldb.org/web/hsqlDocsFrame.html
@hypersql
HSQLDB Development Group
US
2001
Hypersonic SQL
Open Source
Java
All OS with Java VM
BSD
https://en.wikipedia.org/wiki/HSQLDB