HiRDB can use the following DBMSs (Database Management Systems) to implement a distributed database:

• HiRDB at other nodes
• XDM/RD (including XDM/RD E2)
• ORACLE
• RDB1 E2
• SQL/K

A distributed database between HiRDB and a DBMS of another node is implemented using the remote database access facility of DF/UX (Distributing Facility/for UNIX).

Accessing a distributed database involves multiple DBMSs that run on multiple nodes in a network (e.g., server machines, host computers, and PC servers). Each DBMS identified on the basis of its location in the network is called an RD-node. However, because multiple DBMSs may be active at the same time at a single node or a single DBMS may be active by linking multiple nodes, there is not necessarily a one-to-one relationship between RD-nodes and nodes in the network. Therefore, a DBMS and the databases managed by that DBMS may sometimes be referred to collectively as an RD-node.

An RD-node is identified by an RD-node name, and the HiRDB that is connected using a CONNECT statement without RD-node name specification (HiRDB specified at the connection-destination by the client environment definition) is called the default RD-node. RD-nodes other than the default RD-node are called distributed RD-nodes, which also include DBMSs other than the HiRDB.