[Info-vax] Migrating from Rdb to Open Source Postgres

[Denys Beauchemin]

Over the last several years, Postgres has acquired a solid reputation as a dependable, mission-critical RDBMS.  One of its benefit is that it’s Open Source, ie, license free.  You can install it on as many servers as you want, with any number of CPUs, for any number of users, no charge.  

A few years back, VSI released the Postgres client on VMS, and we at Sector7 worked with them to expand a few limitations for handling large schemas.  We used our automated tool to transform the SQLMODs into equivalent procedures that access Postgres instead of Rdb.  The argument list for the procedures was the exact same as the SQLMODs, so the application programs did not need any modification.  Just link the executables with Postgres library and the converted procedures and run the program as before.

The Postgres server runs on Linux, and the application access the Postgres database over the network.  We used this technology to migrate IKEA’s store application that runs on OpenVMS on a server at every store around the world, to access a new Postgres server in every store. The application remained on OpenVMS and the Rdb service could be stopped, returning a bunch of cycles back to the application.

This was all using Open Source Postgres and the Open Source client, supported by VSI, on OpenVMS.  The application got a performance improvement, and in certain cases, a sizable improvement and best of all, now that the application data is in Postgres, it can be accessed by a multitude of tools and apps on various platforms.  The application running on OpenVMS is no longer an island in the enterprise.