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REDUCED and the SPARQL XML Results Format

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Wed, 21 Mar 2007 14:39:31 +0000
Message-ID: <460143A3.3000207@hp.com>
To: dawg mailing list <public-rdf-dawg@w3.org>

There is an interaction between REDUCED and the SPARQL Query Results XML
Format [1].  The results format defines a variable binding form [2] which
includes a 'distinct' attribute:

<results distinct="false">

Which brings up the question of what happens with a REDUCED query?

We could add a similar 'reduced' attribute, which could not be present when 
'distinct' is, or have both and only one can be true.  An alternative design 
is have a single attribute/value of something like: 
"cardinality=distinct/reduced/all" which is more disruptive.

But because the cardinality of REDUCED is not completely defined, there is 
no need to do anything: the results could just come back with 
distinct="false" and no promise is broken.

So significant here is what use is made, for real, of the attributes in 
SPARQL results files (which are in CR).  If the answer is "not much" then 
not doing anything is more acceptable to me.  If we know of a significant 
use, we need to see the impact.

I don't know of any use of the attributes other than just to record 
information that is also in the query request.

Subsidiary questions:

If there is way to indicate "reduced", and the service implementation of 
REDUCED is to do "all" for this service request, can the service just omit 
the reduced because results are all present?

If there is way to indicate "reduced", and the service implementation of 
REDUCED is to do DISTINCT?  Is it permissible to set the 'distinct' 
attribute true? Woudl we recommended to doing so?

The JSON format [3] is also impacted.


[1] http://www.w3.org/TR/rdf-sparql-XMLres/
[2] http://www.w3.org/TR/rdf-sparql-XMLres/#vb-results
[3] http://www.w3.org/TR/rdf-sparql-json-res/
Received on Wednesday, 21 March 2007 14:40:22 UTC

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