[Mulgara-dev] Adding extensions in SPARQL

[Paul Gearon]

On Tue, Feb 24, 2009 at 3:42 AM, Agustina Martinez <amgcia at gmail.com> wrote:
> As you know, I am working with the SPARQL Endpoint. The extension functions
> like "count" or "min" are not available in SPARQL language but in iTQL they
> are. Do you have any plans of adding those functions to the SPARQL endpoint?

No. The language constructs don't exist for this, so there's no
effective way to approach it. The best I'd be prepared to offer would
be to give a count of the overall size on a HEAD request (usual
queries are GET requests).

"Count" and other aggregation functions are a common request, and are
very likely to make it into SPARQL 2. However, the working group for
SPARQL 2 hasn't been formed yet*, so it's still a long way off.

> We are using visualisation tools to present the results obtained but we need
> to constraint the size of the results displayed.

It sounds like you're just looking for LIMIT and OFFSET, but since you
want "count" then I'm not sure that I'm following you correctly.

> Other option goes to
> explore Mulgara code and try to implement count for SPARQL, but I am a bit
> lost on where to start looking at.

The issue isn't how to implement it in SPARQL. We already have this
function in TQL. The issue is how to represent it syntactically and
semantically in SPARQL.

* Right? David? Andy?

Regards,
Paul Gearon