ADABAS
A relational database system by Software AG. While it was initially designed for large IBM mainframe systems (e.g. S/370 in the late 1970s), it has been ported to numerous other platforms over the last few years such as several flavors of Unix including AIX.
ADABAS stores its data in tables (and is thus "relational") but also uses some non-relational techniques, such as multiple values and periodic groups.