[xquery-talk] Linking Saxon through to exist database

Dave Pawson dave.pawson at gmail.com
Sun Jan 25 08:50:50 PST 2009

2009/1/24 Michael Kay <mike at saxonica.com>:
>> Can I connect a query to that database and use Saxon for the
>> query engine?

> You're not going to see Saxon decomposing your query (or XPath expression)
> and shipping parts of it to eXist to take advantage of eXist's indexes, or
> to retrieve only the parts of the documents that your expression actually
> needs. That's not because it's technically infeasible, but because it's a
> pretty sophisticated piece of technology that would cost a lot to develop
> and test and would be priced correspondingly.

Andrew mentioned the data model as another factor.
The sophisticated indexing (giving the speed hike) does make sense
and a big difference.

Any idea if W3C considered 'standardising' some part of this
(no idea of this makes sense or not) to enable such a mix and match,
or is that clearly in the implementation arena?

> The DataDirect XQuery engine does this kind of query decomposition to access
> data from multiple data sources, but as far as I know it currently accesses
> only relational back-end databases and XML in filestore, not XML databases.
> I'm sure the technology is quite capable of accessing an XML data source,
> but the cost of integrating each supported data source is likely to be high.

And you'd need to do this for each XML datastore. Not really practical I guess.


Dave Pawson
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