[Info-vax] a cool database... as replacement for RMS index-sequential files:: Was: VSI working on alternatives to Oracle Classic database:

[Arne Vajhøj]

On 1/20/2021 12:06 PM, gérard Calliet wrote:
> Le 20/01/2021 à 16:40, Arne Vajhøj a écrit :
>> For an existing VMS application then converting is most likely a good
>> thing in the long perspective, but since it means changes, then
>> it needs some analysis on when to do it.
> My question is just about that.
> 
> I received a lot of opinions about conversion from applications based on
> indexed-sequential to relational database which are saying it represents
> a huge structural transformation, because of the very different
> philosophies (for example about how to normalize, how to deal with cobol
> redefines or occurs clauses, etc,...).

The basic data mapping should not be that difficult.

record type -> table
field -> field

will provide a basic table structure.

Then optionally one can do a bit of normalization and move repeating
items to a separate table to get to 1NF.

Then onto operations.

Reading a record become doing a SELECT.

Writing a new record becomes an INSERT.

Updating an existing record becomes an UPDATE.

It is obviously work. Any software change is work. But it
may not be so bad.

There are also a few potential gotchas:
* no fixed record types in which case a relational database
   may not be a good choice and a NoSQL Document Store may be better
* low level persistence structures having leaked high up in
   the layers requiring significant code change

> But perhaps something can be done and there are innovative methods for
> that. I have not a definitive opinion on that. And because of what you
> have told, I was a little bit curious.

I don't think there is any silver bullet.

Arne