I came across an old RDBM called Business System 12
(http://www.mcjones.org/System_R/bs12.html) a few days ago. It seemed
to have a much simpler method of specifying queries - more similar in
style to relation algebra than SQL. For example, some example code
might look like this.

view = join(rel_1, rel_2) --assertains join criteria
based on primary keys
filtered_view = select(condition_list, view)
result = project(attribute_list, filtered_view)

Ignoring for a minute that SQL is the accepted method of talking to
databases, and also acknowledging that SQL may be more expressive than
relational algebra, I wondered if it would be possible to extend
Postgresql to allow non-sql interfaces to simple database services.

I suppose it would be possible to convert statements like those above
into their SQL equivalent before passing them to an existing driver, but
from reading the docs, it seems that dbmses usually do these types of
operations once they have parsed the SQL anyway.

I'd be interested to hear your thoughts on the subject whatever they
are. Critical comments are particularly welcome (they might be quite
useful for getting this stupid idea out of my head ;-)).

Regards,
Andy


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As an academic exercise it would be interesting to try and create the
*next* RDBMS query language. In a production environment I do think the
idea is crazy.

I've got a little experience with this. Interbase used to support a more
procedural query language called GDML (along with SQL). I used it in a
production system. I had a reason, which was that it supported
multi-threading (like SET CONNECTION does in more recent SQL.) In
retrospect, it was a lousy decision.

First off, it wasn't all that popular, and Borland dropped support for it.
So much for maintenance. I was one of very few people who bothered to
learn it. Great job security, if you want to maintain a legacy system as a
job your locked into. Trained programmers, evolving capability, and a
helpful user community was nonexistent. You got a problem? You're on your
own.

Rick

pgsql-general-owner@postgresql.org wrote on 03/31/2005 07:46:02 PM:

> I came across an old RDBM called Business System 12
> (http://www.mcjones.org/System_R/bs12.html) a few days ago. It seemed
> to have a much simpler method of specifying queries - more similar in
> style to relation algebra than SQL. For example, some example code
> might look like this.
>
> view = join(rel_1, rel_2) --assertains join criteria
> based on primary keys
> filtered_view = select(condition_list, view)
> result = project(attribute_list, filtered_view)
>
> Ignoring for a minute that SQL is the accepted method of talking to
> databases, and also acknowledging that SQL may be more expressive than
> relational algebra, I wondered if it would be possible to extend
> Postgresql to allow non-sql interfaces to simple database services.
>
> I suppose it would be possible to convert statements like those above
> into their SQL equivalent before passing them to an existing driver, but
> from reading the docs, it seems that dbmses usually do these types of
> operations once they have parsed the SQL anyway.
>
> I'd be interested to hear your thoughts on the subject whatever they
> are. Critical comments are particularly welcome (they might be quite
> useful for getting this stupid idea out of my head ;-)).
>
> Regards,
> Andy
>
>
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> TIP 7: don't forget to increase your free space map settings


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