Oracle Rdb - Definition and Overview

Rdb/VMS is a relational database management system (RDBMS) for the Hewlett-Packard OpenVMS operating system. It was originally created by Digital Equipment Corporation in 1984 as part of the VMS Information Architecture, intended to be used for data storage and retrieval by high-level languages and/or other DEC products such as DATATRIEVE, RALLY, and TEAMDATA.

In 1994 DEC sold the Rdb division to Oracle Corporation where it was rebranded Oracle Rdb. Contrary to popular belief, Oracle is still enhancing and developing this product in 2004 (although "Oracle Database" products like Oracle-10i get the lion's share of Oracle's advertising budget). It currently runs on OpenVMS for VAX and Alpha. Oracle is porting it to OpenVMS for Itanium. It used to run on DEC Tru64 and Microsoft Windows NT, but demand was low, so they were dropped.

Interactive access to the Oracle Rdb can be by SQL (Structured Query Language), RDO (Relational Database Operator), or both.

High level languages usually access Rdb by:

1. embeddeding RDO statements in the source file then running it through a precompiler

   (example: "file.RCO" is pre-complied into "file.COB")

2. embeddeding SQL statements in the source file then running it through a precompiler

   (example: "file.SCO" is pre-complied into "file.COB")

3. placing the SQL statements in a file external to the source code; this separate file is converted to object code by the "SQL Module Language" complier, and the source code then references these SQL statements and, after complilation, the two are joined by the OpenVMS linker.

  example: $SQL$MOD file_bas.sqlmod        -> file_bas.obj
           $BASIC   file.bas               -> file.obj
           $LINK    file.obj,file._bas.obj -> file.exe

A variation of example 3 allows "Dynamic SQL" to be created in the source code, and then used to communicate with Rdb via a structure known as SQLDA (SQL Descriptor Area).

On OpenVMS systems, Oracle Rdb is a popular (although expensive) upgrade path for applications written using indexed Record Management Services (RMS) files, an ISAM technology built directly into OpenVMS.

External link

• OpenVMS: Rdb Notes (http://www3.sympatico.ca/n.rieck/docs/rms_rdb_notes.html)