[Info-vax] Oracle Database vs Oracle/Rdb

[Stephen Hoffman]

On 2019-06-19 05:18:04 +0000, DTL said:

> The Customer wants (why? dunno yet) to "move from Rdb to Oracle" (sic) 
> in the same environment, with no modifications whatsoever.

One of the very few database pairings where I'm aware of that being 
feasible is MySQL to MariaDB, and from MariaDB to MySQL.

With most other database migrations and including between Oracle Rdb 
and Oracle Classic?  Nope.  Code changes are required,  The core of the 
SQL processing will be very similar if not identical, but the rest of 
the baggage—typically backup and maintenance procedures, any embedded 
SQL or other DB-specific features, etc—will require code changes.

There used to be an Oracle Metalink article or two on this topic, and 
that could serve as an introduction to some of what's involved in a 
database port.

The version of Oracle Classic on OpenVMS is fairly old, as compared 
with what's available on other platforms.

For at lest some of the folks using a specific database and its 
features quite heavily, it can be easier to port platforms than to port 
databases.

There are mechanisms that allow querying a remote database from OpenVMS 
too, and which might provide an alternative to a local database 
migration.  Much like the database migration, code changes will be 
required here.  This'll allow use of a newer Oracle database, if that's 
your choice.  VSI has available a database client for PostgreSQL, as an 
alternative—that's a PostgreSQL database client for OpenVMS, and *not* 
a PostgreSQL database server for OpenVMS, some rather confused 
announcements and postings to the contrary.

There are some other database options available for OpenVMS including 
SQLite and MIMER, depending on scale and scope and support 
requirements.  Much of which has been discussed before, and a search of 
the Google Groups newsgroup archives will find various of those 
existing threads.



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