Re: [xsl] [xslt performance for big xml files]

[Robert Koberg <rob@xxxxxxxxxx>]

On Apr 25, 2009, at 10:05 PM, Liam Quin wrote:

> On Sat, Apr 25, 2009 at 07:16:04PM -0400, Robert Koberg wrote:
> > Of all the real world applications deployed that use XQuery (I  
> > suppose
> > I could be more specific and say as recommended by Liam, but maybe
> > probably not necessary), how many do you think would work on more  
> > than
> > one XQuery processor?
>
> I think quite a few, although yes, you generally will have to change
> the collection() and document() arguments.  Try creating a SQL
> database and querying it in Oracle, DB2, MySQL, PostgresQL and you'll
> generally find you have to change the code at least a little, but
> that does not make SQL completely non-interoperable.  It's a case
> of managing expectations, and of "the application was ported in
> a week" vs "we would need to rewrite millions of lines of code from
> scratch".

yes, but people aren't being encouraged to write webapps in SQL. And  
there are tools that allow you to abstract away the differences.

> > [...] XQuery as used/promoted by the XML DBs tend to favor their
> > own extensions in documentation and lists  (though there seems to be
> > more caveats on the lists lately, though).
>
> I don't actually remember which implementations I suggested -- most
> likely MarkLogic, Qizx and dbxml, since I've used them.  I've not
> had major problems moving queries between them, though, once the
> files are indexed, which is a separate (although not unfair) question.
>
> We didn't standardise collection() -- at some point you have to
> say, "this is the scope of our spec" and stop.  Maybe for XQuery 1.1
> we could consider an optional directory-of-files-as-collection()
> function, but then people would say they needed options to say whether
> to re-run indexes, what collation sequences and file encodings to
> assume, whether to follow shortcuts and sumbolic links... and pretty
> soon it'd be a huge mess.  or at least that's been a difficulty in
> the past.  Relational database schemas aren't entirely portable
> either, and neither are filenames (e.g. between MS Windows and
> Solaris and OS X the character sets, lengths, and default encodings
> differ).
>
> You're right that extension functions are a problem -- that's true
> for XSLT as well, of course, and XPath, and for that matter C and
> Perl and Python....

But with XSL and XPath the extensions are really not needed and you  
are not steered away from the standard right away.

best,
-Rob


> Liam
>
> --
> Liam Quin, W3C XML Activity Lead, http://www.w3.org/People/Quin/
> http://www.holoweb.net/~liam/ * http://www.fromoldbooks.org/