TimesTen was originally the SmallBase project out of HP Labs. It was then spun off as a separate start-up.
SQL
B+Tree T-Tree
By default TimesTen uses B+Tree. The original version (SmallBase) from the 1990s supported T-Trees. TimesTen still supports T-Tree indexes but the administrator has to request for the DBMS to use them.
In-Memory
Relational
http://www.oracle.com/us/products/database/timesten/index.html
HP Labs
US
1996
SmallBase
Oracle
Commercial
Linux
Proprietary
https://en.wikipedia.org/wiki/TimesTen