[Info-vax] VSI roadmap

[Dave Froble]

On 8/18/2023 6:45 PM, Arne Vajhøj wrote:
> On 8/18/2023 4:39 PM, Dave Froble wrote:
>> On 8/18/2023 1:58 PM, Jan-Erik Söderholm wrote:
>>> We create the (Rdb) database tables as we need them.
>>> Then extract include files (done with the built-in DBA tool RMU).
>>> The record definitions are loaded into a text library (TLB).
>>> Finally COPY'ed from the TLB into the Cobol source files.
>>>
>>> The RMU tool support extracting records in these languages:
>>> SQL, ANSI_SQL, RDO, C, Cobol and Pascal.
>>>
>>> This replaced the use of CDD that was a hazle to maintain
>>> just for the record definitions.
>
>> Ok, understand what you are doing.
>>
>> Caviet, I've never used Rdb.
>>
>> Another, I've only used SQL2000 from Microsoft.
>>
>> Regardless, consider the following:
>>
>> SELECT * From CustomerTable Where Country is "USA"
>
> SELECT * From CustomerTable Where Country = 'USA'

Come on Arne, give me a bit of a break.  (Not vertibre)  It's been over 20 years 
since I used SQL.  I think I got the idea across.

:-)

>> And where country is not a key.
>>
>> In RMS this cannot be done, without scanning all records, and use some type of
>> mapping of the record definition, CDD, include file, in program definition.
>> However, if the database contains the record definitions, then the database
>> would return a recordset of the records with Country equal to USA.
>>
>> Yes, all records would be scanned internally, but database products do this
>> rather quickly and efficiently, and transparent to the request.  Would work on
>> any system that supports the database.
>
> Internally is a rather similar.
>
> ORG=IDX:
>
> key field => efficient lookup via index
> not key field => full scan
>
> RDBMS:
>
> indexed field =>  efficient lookup via index
> not indexed field => full scan

Doesn't matter for this discussion.

> But seen from the application side the RDBMS is a lot easier:
> * index can be added later if a performance problem is identified
> * most databases allow for many indexes (MySQL allows up to 64 per table)
> * the full scan is done within the database transparently to the
>   application
>   - less application code
>   - no application code changes when switching from not indexed to indexed

This is my point.  When the record definitions (columns) are known to the 
database, it can then use them for operations.  Not so in the design of RMS.  At 
least without such as CDD and custom programs.  Implementing custom utilities 
that will work on any file/table is then possible.

-- 
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef at tsoft-inc.com
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA  15486