I don't have a count query defined because count isn't standardized in SPARQL 1.0 and count queries can also be really heavy.

However, this makes some plugins break.

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netsensei’s picture

netsensei commented

Yup. Noticed this too in D6 version of SV. This made paging harder since I had to retrieve the entire result set and count the number of results in PHP.

It's not just COUNT but aggregate functions as a whole which are lacking in the specification.

More information:

http://www.w3.org/2009/sparql/wiki/Feature:AggregateFunctions

Individual triple store implementations like ARQ do have their own extensions to cope with this. But we can't reliably establish whether or not these are available when you connect to an endpoint.

Anonymous’s picture

Anonymous (not verified) commented

Fortunately, aggregates are defined in SPARQL 1.1, but I don't know when that is due to go to recommendation. One of my advisors is on the working group, so I can ask him what the expected schedule is. It still needs to go to Candidate Recommendation and Proposed Recommendation. And then it needs to be implemented by the vendors... so I'm guessing it will be a while.