[Info-vax] Oracle Database vs Oracle/Rdb

[Jan-Erik Söderholm]

Den 2019-06-22 kl. 02:13, skrev Arne Vajhøj:
> On 6/21/2019 4:48 PM, Stephen Hoffman wrote:
>> 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.
> 
> Porting between two databases sharing most of the source code
> is to be expected to be easy.
> 
>> 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.
> 
> Regarding application code then it all depends on the application.
> 
> It is possible (but maybe not easy) to write portable database code in
> most modern languages and frameworks.
> 
> The chance that is the case for a VMS application using RDB is probably
> small though.

Rdb have had Oracle syntax added over the years from the Oracle
take over of Rdb. Rdb can in many ways look like an Oracle DB.
But then you have to design your source code in that way. It is
probaby more meant for applications that was written for an
Oracle database in the first place.


> 
> The operational side will definitely be different. There are no
> standards for that.
> 
>> 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.
> 
> Again it depends on the application.
> 
> Moving to another platform in this case implies a change
> of database.
> 
> Arne
>