How about reformulating as:
select (count(?s) as ?c) where { select distinct ?s where { ?s ?p []} }
Which gives a result of 10515620 resources [1].
Regards,
John
[1]
http://fr.dbpedia.org/sparql?default-graph-uri=&query=select+%28count%28%3Fs%29+as+%3Fc%29+where+%7B+select+distinct+%3Fs+where+%7B+%3Fs+%3Fp+%5B%5D%7D+%7D&format=text%2Fhtml&timeout=0&debug=on
-----Original Message-----
From: Hugh Williams [mailto:[email protected]]
Sent: Wednesday, July 06, 2016 3:15 PM
To: Jean-Claude Moissinac <[email protected]>
Cc: public-lod <[email protected]>
Subject: Re: Size a linked open data set
Hi Jean-Claude,
The "select count(distinct ?r) where { ?r ?p ?l }” query is expensive in terms
of database resources and would result in a huge hash table being creating to
try and service it which is causing it to timeout based on the settings on the
instance by whoever maintains it.
On http://dbpedia.org/sparql the original canonical English DBpedia endpoint
OpenLink Software hosts, we provide preloaded VOID datasets, such that they
don’t have to be queried each time, see http://dbpedia.org/void/Dataset , but
the French DBpedia instance does not appear to have this ie
http://fr.dbpedia.org/void/Dataset
Best Regards
Hugh Williams
Professional Services
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> On 6 Jul 2016, at 12:49, Jean-Claude Moissinac
> <[email protected]> wrote:
>
> Hello
>
> In my work, I need to know the number of distinct resources in a dataset.
> For example, with dbpedia-fr, I'm trying
> select count(distinct ?r) where { ?r ?p ?l }
>
> And I'm always getting a timeout error message
> While with
> select count(?r) where { ?r ?p ?l }
> I'm getting
> 185404575
>
> Is it a good way to know about such size?
>
> --
> Jean-Claude Moissinac
>
