Pre-and Postrelational Database Management Systems

The pre- and postrelational DBMS market includes multiuser DBMSs that are accessed using explicit navigation of the structure by the problem program and are typically organized using either the CODASYL or a proprietary structure. List-oriented, hierarchical, b-tree indexed, network, and inverted list are examples of organizations included in this category. The following are representative vendors and products in this market:
Prerelational DBMSs:

• Computer Associates (IDMS and DATACOM)
• CCA (Model 204)
• Cincom (Supra)
• IBM (IMS)
• Software AG (Adabas)
• Postrelational DBMSs:
• InterSystems (Caché)
• Polyhedra (Polyhedra