[Info-vax] The best VMS features, was: Re: openvms renaming file

[Arne Vajhøj]

On 5/28/2018 4:08 PM, Johnny Billquist wrote:
> On 2018-05-28 20:56, Simon Clubley wrote:
>> RMS ISAM files would still be very limited compared to a database,
>> even MySQL.
>>
>> For example, compare what is involved in adding a new field to
>> a database compared to what is involved in adding that same field
>> to a RMS ISAM file.
> 
> Technically, this is not really a problem in RMS, but one of most 
> applications using RMS. Most applications are pretty hardcoded how they 
> expect the file to appear, and so any change will cause big issues.
> 
> The designers of RMS, however, obviously, intended that clever 
> application writers would not be limited in such a way.
> 
> Adding a field, as such, is just a question of copying the file, and 
> adding that field in all records. There are tools that easily can do 
> this. RSX comes with such tools in the standard RMS toolbox. I would 
> assume VMS have similar, or more capable tools.
> 
> Applications could be clever enough to actually refer to fields based on 
> names, instead of just using fixed, known, chunks of the record. RMS do 
> have names for the fields, which you can set and read. And then you 
> could base your access on this information, in which case a change of 
> the file presents no problem at all.
> 
> However, admittedly, I doubt any application (more or less) actually do 
> this. But do not blame RMS for this.

It may not be an architectural limitation in RMS, but VMS does not
ship with a utility to do stuff like this and VMS does not ship
with a library that makes it easy to write code that do such stuff.

Embedded database does.

Arne