Re: Re: abstract data types? - Mailing list pgsql-sql

John,

> Thanks for your comments. My 2c worth:

That was at least $1.50 worth.  Teach me to speak 'off the
cuff' on this list ...

> As
> far as the 
> relationship between the schemas for financial and
> spatial information 
> systems goes, a book I have (on OO database management)
> goes so far as 
> to say "that relational database systems do not
> adequately support these 
> so-called non-standard applications."

I'd agree with you, I'm afraid.  Most of the "spatial
database projects" I've been familiar with involved either:
a) completely custom software, or b) *lots* of RAM and
processing power, or c) both.

> Unfortunately I can't speak from personal
> experience - I 
> don't have any access to it, as at uni we are a Oracle/MS
> SQL 
> Server/mySQL shop, and from my preliminary investigations
> none of these 
> seem to cut it for this task as far as I am concerned :-(

A definite No for 2 of the above.  MySQL was built to be
fast and light, with a minimal feature set.  As a
semi-certified MS SQL Admin, I can tell you that MS SQL
Server isn't up to anything better than a *simple*
accounting database.  Oracle, on the other hand, claims to
do anything.  They really have no geometic support?

> Interesting. This is a really cool site. Thanks. However
> I don't see how 
> you draw the conclusion from what I have read on this
> site "that 
> object-oriented and relational approaches to data
> problems *cannot* be 
> made to reconcile." C.J. Date here seems to be arguing
> more about the 
> semantics employed in UML modelling, Pascal more about
> the quality of 
> database design. This site does give me the urge to read
> up on set 
> theory - I've forgotten what little I once knew.

You're right, that's what's currently on the site.  I'm
basing my opinion more on the earlier writings of Pascal ...
and porbably on my own expereinces.  Of course, we could ask
him.

> In [DAT00] (Section 25.1 pg 863) Date states "we need do
> nothing to the 
> relational model in order to achieve object functionality
> in relational 
> systems - nothing, that is, except implement it, fully
> and properly, 
> which most of today's systems have so signally failed to
> do."

Yeah.  Few systems bother even to fully implement the SQL
standard fully ... and SQL 99 was as much a product of
politics in the computer industry as logic.

For example, I agree with Pascal & Date that BLOBs are a bad
idea, and a violation of relational priniciples (being data
that cannot be stores as a value in a column in a relation).
One need only look at the terrible and persistent
implementation problems for BLOB support in various
platforms for proof of this.
  
> He then states that "the support is already there [in the
> relational 
> model -jgr], in the shape of domains (which we prefer to
> call types 
> anyway)."
> 

Yeah.  Real DOMAIN and TYPE support (which are really two
diffetent things, a Domain being a specification for a more
general Type) in Postgres would be teriffic.  How about it,
Tom, Stephen?

> Chapter 1, pg 6). Interesting, I just noticed the
> statement "is truly 
> relational (unlike SQL)."!

Yes -- see my comments above.  Market pressues and politics
have caused the ISO to abandon relational standards in
formulating the SQL standard in many areas.

> Sorry, disagree strongly here. 

Ok.  I'm probably just biased, anyway, from being burned by
DB tools claiming both OO and SQL-relational support.

> As far as I can tell, PostgreSQL has most, if not all, of
> the building 
> blocks to supply support for abstract data types already
> in place. 
> Whoever thought up the system catalogs (as well) was one
> very smart 
> individual. Salutations, whoever you are!

I'd definitely stand back and applaud any effort to support
this.  When I first started with PostgreSQL, I thought it
was a really nifty idea, until I tried to build a database
on it.  Puls I soon discovered that nifty ideas do not a
payment-processing database make :-(

> Any help people can give me would be much appreciated.
> I'm already 
> feeling a little lost. I hope people don't mind if I ask
> a lot of dumb 
> questions over the next few weeks :-) Is this the
> appropriate list, or 
> should I move over to hackers?

You should probably cross-post.  This list is the place to
see if a number of other developers are interested in the
functionality you propose (yes), hackers is probably the
place to ask how to make the actual changes.

I can't help.  Heck, I can't even get 7.1 beta to run on an
alternate port.

-Josh Berkus

P.S. BTW, John, I'm thrilled to get a discussion of issues,
going here in addition to the how-tos!