Anthony,

> And don't other databases have both theory and model?

Actually, no, the "new" databases do not.  

The relational model is backed by relational algebra and relational calculus, 
plus a series of postulates and laws which have been refined and tested over 
20 years.   

Not Object-Oriented databases nor XML "databases", nor Multi-Value databases 
have any body of theory behind them, mathematical or otherwise.   I defy you 
to post a single paper that has a mathematical theory for MV or OODB, or even 
a firm set of laws that govern such a database.   Nor is the industry moving 
toward developing such a theory; instead the marketeers of commercial OODB 
and XMLDB use a lot of ink to denigrate the idea of mathematical theory as 
antiquated and stuffy, and in one case even using their advertising clout to 
drive critical theorists off the pages of IT magazines (see Fabian Pascal's 
web page).

Actually, amusingly enough, there is a body of theory backing XML databases, 
but it's not one any current devloper would want to admit to: the XML 
database is functionally identical to the Network Databases of the 1960's.   
Of course, Network Databases gave way, historically, to Relational for good 
reason.  

And MV databases, despite decades of existence, never developed any theory 
behind them at all, possibly because one is not possible; MV databases are 
entirely an ad-hoc creation designed to work around decade-old limits in 
computer processing.  Pick is merely TextMagic revived and put on the web.

Now, OODB could certainly *develop* a model and theory, and I think it's high 
time it did.   The Zope project has amply demonstrated the usefulness of OODB 
for certain applications.   But as long as there is no OODB calculus, and no 
industry-agreed model, and no ANSI standard language or interface, each and 
every OODB will be 100% incompatible with every other one ... severely 
limiting their utility.

The importance of theory, model, and standards is *not* to be overstated in an 
industry where every year the industry-favorite commerical databases get more 
ad-hoc, further from the theory, and more callous in their disregard of 
international standards.

FWIW, I share your dissatisfaction with SQL, but because it's not relational 
enough rather than the other way around.

-- 
Josh Berkus
Aglio Database Solutions
San Francisco

Sun, 19 Oct 2003 12:24:13 -0700
Josh Berkus <josh@agliodbs.com>
Re: Dreaming About Redesigning SQL
>>>>> "Josh" == Josh Berkus <josh@agliodbs.com> writes:

This is an unfair characterization of XML databases, and I can say
this without accusations of bias for I vastly prefer working with the
relational model. 

    Josh> Actually, amusingly enough, there is a body of theory
    Josh> backing XML databases, but it's not one any current devloper
    Josh> would want to admit to: the XML database is functionally
    Josh> identical to the Network Databases of the 1960's.  Of
    Josh> course, Network Databases gave way, historically, to
    Josh> Relational for good reason.

If you look at the academic research work, there have been gazillions
of recent papers on XML database technology. All the major database
vendors (Oracle, IBM and Microsoft) are investing fairly heavily in
core-engine XMLDB technology. 

Finally, while it is true that some of XML db technology is evocative
of network databases, XML databases are certainly more than network
databases. For one, they are semi-structure .. in addition they
present query language access to their data (although I'm not a big
fan of XQuery).

-- 
Pip-pip
Sailesh
http://www.cs.berkeley.edu/~sailesh



Sun, 19 Oct 2003 17:29:37 -0700
Sailesh Krishnamurthy <sailesh@cs.berkeley.edu>
Re: Dreaming About Redesigning SQL
In an attempt to throw the authorities off his trail,
sailesh@cs.berkeley.edu (Sailesh Krishnamurthy) transmitted:
>>>>>> "Josh" == Josh Berkus <josh@agliodbs.com> writes:
> This is an unfair characterization of XML databases, and I can say
> this without accusations of bias for I vastly prefer working with
> the relational model.
>
>     Josh> Actually, amusingly enough, there is a body of theory
>     Josh> backing XML databases, but it's not one any current devloper
>     Josh> would want to admit to: the XML database is functionally
>     Josh> identical to the Network Databases of the 1960's.  Of
>     Josh> course, Network Databases gave way, historically, to
>     Josh> Relational for good reason.
>
> If you look at the academic research work, there have been
> gazillions of recent papers on XML database technology. All the
> major database vendors (Oracle, IBM and Microsoft) are investing
> fairly heavily in core-engine XMLDB technology.

Ah, but do "papers" honestly indicate the emergence of some underlying
theoretical model for which fidelity could be evaluated?  

Or merely that academics are looking to write papers on whatever
topics can attract research funding?

Half the articles in SIGOS have been about pretend applications of
Java to operating systems; why does it seem likely that the "database
academics" are any less affected by this?

I haven't yet seen a coherent "XML theory" emerge from the chaos.

It's not too dissimilar from the "object chaos;" the only works I am
aware of that try hard to provide theory behind "object orientedness"
are _A Theory of Objects_ by Abadi and Cardelli, and Benjamin Pierce's
book, _Types and Programming Languages_.  After twenty-odd years of
object oriented programming, I find it quite appalling that there is
as little theoretical OO literature as there is.

> Finally, while it is true that some of XML db technology is
> evocative of network databases, XML databases are certainly more
> than network databases. For one, they are semi-structure .. in
> addition they present query language access to their data (although
> I'm not a big fan of XQuery).

CODASYL had a query system, albeit something that looked more like
assembly language than anything else...
-- 
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http://www.ntlug.org/~cbbrowne/nonrdbms.html
Rules of  the Evil Overlord  #63. "Bulk trash  will be disposed  of in
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Sun, 19 Oct 2003 22:47:29 -0400
Christopher Browne <cbbrowne@acm.org>
Re: Dreaming About Redesigning SQL
Sailesh,

Warning:  I get carried away in this response.   I'm afraid that I'm a fond 
reader of Fabian Pascal and CJ Date, so I have far too much to say on the 
topic.   So if you really care about XML databases, you should probably hold 
off on reading the rest until you're well-caffinated and in a cheerful frame 
of mind.

Also, let me clarify that there is a distinction between using XML *as a* 
database, and putting XML documents into databases of other types.   I find 
the latter obvious and sensible, but the former a silly and wrong-headed 
idea, and it's the pure-XML-database which I attack below.

If you want to really have this out, I live in San Francisco and I love to 
argue.  Coffee at Intermezzo?  I'll buy.

-------------------------------
> If you look at the academic research work, there have been gazillions
> of recent papers on XML database technology.

Point me to one which presents an algebra, calculus, or other mathematical 
underpinning of XML databases, and I will be happy to eat my words on this 
list.   I can easily find lots of papers using google, but all of them are 
about *technical implementation* and do not provide a theoretical 
underpinning for XML databases.  

A few (such as Dan Suciu's paper) present some theory to back XQuery but it is 
presented entirely as an XML-based data access extension to SQL ... a role 
which seems fine to me.  

Others, even those cited by xmldb.org like the below, have rather lukewarm 
things to say on the topic, such as David Mertz, PhD:
(http://www-106.ibm.com/developerworks/library/x-matters8/index.html)

"XML is an extremely versatile data transport format, but despite high hopes 
for it, XML is mediocre to poor as a data storage and access format. ..." 
<snip>
" ...XML has no inherent mechanism for enforcing constraints of this sort 
(DTDs and schemas are constraints of a different, more limited sort). Without 
constraints, you just have data, not a data model (to slightly oversimplify 
matters). ..." <snip>
" ... In other words, go ahead and be excited by XML's promise of a universal 
data transport mechanism, but keep your backend data on something designed 
for it, like DB2 or Oracle (or on Postgres or MySQL for smaller-scale 
systems)."

And this guy is cited by XMLDB.org?   Perhaps not surprising, as among the 5 
goals of XMLDB.org, development of a standard theory of XML databases is not 
present.  

>  All the major database
> vendors (Oracle, IBM and Microsoft) are investing fairly heavily in
> core-engine XMLDB technology.

So?   Oracle, IBM and Microsoft also have SQL databases that do a terrible job 
of upholding the SQL standard, and their (at least Oracle's and Microsoft's) 
adherence is getting worse with successive versions rather than better. I 
wouldn't look to them for guidance.  

If they're spending millions on XML Databases, it's becuase it, however 
wrong-headed, is a fad and fads mean sales, and they don't want to take a 
chance on missing out.  And these companies have backed plenty of useless 
technologies before; remember Microsoft's "Periodicals on CD"?  

Not that I'm against XML; as far as I'm concerned, for interchangable, 
searchable, and archival documents, XML is the greatest thing since sliced 
Beatles.   I love XML-RPC for pushing data through HTTP, and I will happily 
be in the cheering squad for anyone who writes a set of OSS tools to extract 
data from XML docs stored in a PostgreSQL database, or to automate 
some-standard-XML-to-relational-data-and-back conversion.   That is a good 
application of XML+Database ideas.

XML databases, on the other hand, are an example of taking a good idea too 
far.  XML is a great data transmission tool; it's a great document 
transformation tool; it's a good way to store documents.   It is not, 
however, a good database.
------------------------------------------------------
-- 
Josh Berkus
Aglio Database Solutions
San Francisco

Sun, 19 Oct 2003 22:19:00 -0700
Josh Berkus <josh@agliodbs.com>
Re: Dreaming About Redesigning SQL
>>>>> "Christopher" == Christopher Browne <cbbrowne@acm.org> writes:


    Christopher> Ah, but do "papers" honestly indicate the emergence
    Christopher> of some underlying theoretical model for which
    Christopher> fidelity could be evaluated?

Certainly. The model is that of semi-structured data, where often
times schema isn't very clearly defined. It's a different model from
the relational model - which I'm partial to. There are situations
where the XML model does make sense. 

    Christopher> Or merely that academics are looking to write papers
    Christopher> on whatever topics can attract research funding?

Bash academics if you want. The truth is that industry is also working
on it. 

As I said before, I have no axe to grind in this. I might be in
academia now, but frankly I couldn't give a toss about XML.

    Christopher> Half the articles in SIGOS have been about pretend
    Christopher> applications of Java to operating systems; why does
    Christopher> it seem likely that the "database academics" are any
    Christopher> less affected by this?

I think you are looking at the wrong publishing location :-) The
premier venue for the OS community are the SOSP and OSDI
conferences. Please look at the SOSP04 papers - you'll find fairly
good systems work.

BTW, I'm not sure which database papers you read - the premeer venues
for database systems work are the SIGMOD and VLDB conferences. 

    Christopher> CODASYL had a query system, albeit something that
    Christopher> looked more like assembly language than anything

Please take a fair look at the XQuery data model and the XQuery
language before comparing it with CODASYL. I will not admit (at least
in public :-) to being a big fan of XQuery but that is because of
certain details, not anything fundamental. 

-- 
Pip-pip
Sailesh
http://www.cs.berkeley.edu/~sailesh



Sun, 19 Oct 2003 22:26:50 -0700
Sailesh Krishnamurthy <sailesh@cs.berkeley.edu>
Re: Dreaming About Redesigning SQL
sailesh@cs.berkeley.edu (Sailesh Krishnamurthy) writes:
>>>>>> "Christopher" == Christopher Browne <cbbrowne@acm.org> writes:
>     Christopher> Ah, but do "papers" honestly indicate the emergence
>     Christopher> of some underlying theoretical model for which
>     Christopher> fidelity could be evaluated?
>
> Certainly. The model is that of semi-structured data, where often
> times schema isn't very clearly defined. It's a different model from
> the relational model - which I'm partial to. There are situations
> where the XML model does make sense.
>
>     Christopher> Or merely that academics are looking to write
>     Christopher> papers on whatever topics can attract research
>     Christopher> funding?
>
> Bash academics if you want. The truth is that industry is also
> working on it.
>
> As I said before, I have no axe to grind in this. I might be in
> academia now, but frankly I couldn't give a toss about XML.

Fifteen years ago, there were _vital_ things going on in academia;
Stonebraker's group was assortedly working on Postgres, Ingres, and
Cohera.  _Real_ OS research was going on, with active work on such
systems as Sprite, BSD, Mach, with _many_ schools building their own
OS kernels to explore different edges.

The problem is that with the dearth of funding for "basic research,"
academia seems to be getting used as a partly-government-funded
"development" area for the developments that industry hopes might work
but where they would rather evade responsibility for the failures.

>     Christopher> Half the articles in SIGOS have been about pretend
>     Christopher> applications of Java to operating systems; why does
>     Christopher> it seem likely that the "database academics" are any
>     Christopher> less affected by this?
>
> I think you are looking at the wrong publishing location :-) The
> premier venue for the OS community are the SOSP and OSDI
> conferences. Please look at the SOSP04 papers - you'll find fairly
> good systems work.

When the first paragraph of the annual report contains the phrase

   ... despite the "operating systems" in our name ...

I can't see this boding well for the area of "operating systems
research" being particularly vital.  They have had to expand it to
some notion of "systems" that is sufficiently wide open that I'm not
sure what it _wouldn't_ admit as "relevant."

> BTW, I'm not sure which database papers you read - the premeer
> venues for database systems work are the SIGMOD and VLDB
> conferences.

I haven't been subscribing to anything for a couple years now, TODS
having pretty much fallen into irrelevance.  I suppose I need to look
to see if there is something worth following again.

>     Christopher> CODASYL had a query system, albeit something that
>     Christopher> looked more like assembly language than anything
>
> Please take a fair look at the XQuery data model and the XQuery
> language before comparing it with CODASYL. I will not admit (at
> least in public :-) to being a big fan of XQuery but that is because
> of certain details, not anything fundamental.

I have used it a bit for extracting data out of SOAP requests; I
wasn't terribly impressed with it, finding that with the way it was
remapping data, I would commonly have to code my own "tree walker" to
do things _right_.

It's not hard to do; when I had to modify my Galeon "bookmark walker"
a few months ago when they changed from a custom XML form to RDF, I
was pleasantly surprised to find that most of the changes involved
changing names of tags in DEFCONSTANT declarations.  (Guess the
language :-).)  Of course, "web bookmark" systems are likely to be
structured similarly, so that this change would be easy shouldn't be
much of a surprise.

But when you need to write code, that indicates that there is some
weakness to the model...
-- 
let name="cbbrowne" and tld="libertyrms.info" in String.concat "@" [name;tld];;
<http://dev6.int.libertyrms.com/>
Christopher Browne
(416) 646 3304 x124 (land)

Mon, 20 Oct 2003 10:34:49 -0400
Christopher Browne <cbbrowne@libertyrms.info>
Re: Dreaming About Redesigning SQL