Release of the GCX XQuery EngineQ

[Frans Englich]

On Tuesday 30 January 2007 18:44, Stefanie Scherzinger wrote:
> Dear all,
>
> you might be interested in our new XQuery engine "GCX"
> which is now available for download.
>
> We have just released the first version of GCX as open-source
> software under the Berkeley Software Distribution license (BSD).
>
> GCX is an in-memory query engine designed for memory-efficient
> XQuery evaluation against large XML documents. The prototype
> supports a powerful fragment of the XQuery language, with nested
> for-expressions, child- and descendant axes, and joins.

Sounds interesting.

> The C++ source code, binaries for Linux and Windows, and more
> about GCX can be found at
>
>     http://www.infosys.uni-sb.de/projects/streams/gcx/
>
> Your feedback, questions, and suggestions for improvement are all welcome.

About the comparison on:

http://www.infosys.uni-sb.de/projects/streams/gcx/benchs.php

Aside from the numbers, this paragraph can be found:

"As the GCX engine does not support the full XQuery standard, queries were 
adapted accordingly [...] since GCX does not support attribute access, 
attributes in the XML stream have been rewritten to subelements"

What made you think that comparing your implementation to the others was 
reasonable?

I'm asking because I see it as comparing apples against oranges. Some of the 
other products run the queries as is and they implement XQuery, which is 
quite different from not implementing XQuery and rewriting queries to ones 
liking.

Measuiring memory usage with top is as far as I know generally adviced 
against. See:

http://ktown.kde.org/~seli/memory/analysis.html

So the short story to why you get such a low memory foot prints is that you 
don't load more of the document than is needed, as told my static 
analysis("roles")?


Cheers,

		Frans