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

[Johnny Billquist]

On 2018-05-28 20:56, Simon Clubley wrote:
> On 2018-05-28, Dave Froble <davef at tsoft-inc.com> wrote:
>>
>> I don't think so.  RMS indexed files allow concurrent use, using the DLM.
>>
>> The problem with RMS isn't the design, it's the implementation.  Modern
>> RDBMS systems do much of their work in memory.  RMS does the work on
>> disk.  Quite a large difference in speed, as one might expect.
>>
>> Re-implement RMS in the same manner and you'd see totally different
>> performance.  Ya got to remember how old the design and implementation
>> of RMS is.  40 years ago it worked well.
>>
> 
> 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.

If you ever take time to learn how Google's bigtable works, you'll see 
that it is almost identical to how RMS works. Quite funny, actually.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
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