[xquery-talk] Release of the GCX XQuery EngineQ

[Marc Van Cappellen]

inline

> -----Original Message-----
> From: stefanie.scherzinger at gmail.com
> [mailto:stefanie.scherzinger at gmail.com] On Behalf Of Stefanie
Scherzinger
> Sent: Wednesday, February 07, 2007 11:28 AM
> To: Jonathan Robie
> Cc: talk at x-query.com; Marc Van Cappellen
> Subject: Re: [xquery-talk] Release of the GCX XQuery EngineQ
> 
> > In order to be a little more concrete, I talked with Marc about some
> > comparisons we did internally between GCX and DataDirect XQuery. I
think
> > the results fall out roughly as follows:
> >
> > - Our XMark performance results are broadly similar to those of GCX
for
> > our currently released software. The upcoming DataDirect XQuery 3.0
will
> > be markedly faster in some cases - for instance, for one XMark
query, we
> > finished more than 100 times faster.
> 
> I assume that the one XMark query where you outperform us in runtime
> is the one with the join, where we still only have a naive nested-loop
> implementation.
> 
> > - Our memory usage was similar for many queries, worse for some, and
> > better for others.
> 
> This is very interesting, do you think we could include experiments
> with your product on our benchmark site?

Let's discuss this offline

> 
> > As Marc indicated, we support both document projection and streaming
(as
> > described in A. Marian and J. Simeon, "Projecting XML Documents",
Proc.
> > VLDB 2003, a really cool and useful paper).
> 
> Out of curiosity - does your projection strictly adhere to the
> technique described in this paper? GCX projection is similar, but it
> is also capable of omitting inner nodes. For instance, to project for
> the path //a in <x><b><a/></b></x>, the x- and b-labeled nodes are not
> buffered by GCX. Interestingly, this can really make a difference when
> projecting very large XML documents, even if they are shallow.

Yes, various improvements have been implemented. This is one of them.

> 
> Steffi