[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XQuery and DTD/Schema?
I agree with you 100%. Here's a quote [without permission] from one of our XQuery developers which I doubt ever bubbled back the XML Query WG. "Before proposing a solution, I'd suggest establishing what problems the [XQuery] type system is trying to solve: Validating external inputs and/or generated outputs? Converting between lexical representations and values (formatting/parsing)? Eliminating common user errors at compile-time? Working with structures as first-class citizens (that can be passed around to functions, etc.)? Optimizing execution performance? Proving correctness of query normalizations? Pruning the set of applicable query normalizations at any given expression (optimizing optimizer performance)? Other things I've not considered here? I think the current type system confuses these goals into a mushy complex system of rules, and would benefit from better factoring. I also think the current type system actually fights against some of these goals, instead of supporting them. To give two examples, I believe the current dynamic type checking rules slow performance instead of improving it; and the complex static type inferencing rules obfuscate user errors instead of catching them." Personally I think the W3C XML Query working group is divorced from reality and dogmatically following the action items on its charter without actually thinking through the practicality of the specification they are building. However, come when XQuery reached recommendation status we will ship a kickass XQuery implementation. Believe that. :) C'est la vie. --- Joe English <jenglish@f...> wrote: > > > Queries on large sets of data *do* need to be > efficient - and when you want > > to be efficient, you try to avoid actually > retrieving the data whenever > > possible. Reasoning about types statically is one > of the ways we do this. > > > I still don't buy this argument. > > Static typing can help optimize low-level operations > that are > close to the machine (for instance this is why as a > rule SML is > more efficient than Scheme), but languages that do > heroic > optimizations -- APL, SQL, and Common Lisp for > instance -- tend > to be dynamically typed. Static typing is neither > necessary > nor sufficient. > > What optimization strategies does the XQuery type > system enable? > Has anyone implemented, or even just designed, a > database access > optimizer that takes advantage of it? > > > --Joe English > > jenglish@f... > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org > <http://www.xml.org>, an > initiative of OASIS <http://www.oasis-open.org> > > The list archives are at > http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the > subscription > manager: <http://lists.xml.org/ob/adm.pl> > ===== THINGS TO DO IF I BECOME AN EVIL OVERLORD #79 If my doomsday device happens to come with a reverse switch, as soon as it has been employed it will be melted down and made into limited-edition commemorative coins. __________________________________________________ Do You Yahoo!? Sign up for SBC Yahoo! Dial - First Month Free http://sbc.yahoo.com
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