Greetings,
The problem remains, the following query doesn't execute on the public
DBPedia
endpoint<http://dbpedia.org/snorql/?query=select+distinct+%3Fproperty+where+{%0D%0A+++++%3Fs+%3Fproperty+%3Fo.%0D%0A}+limit+1>,
even with a limit:
select distinct ?property where {
?s ?property ?o.
} limit 1
Without 'distinct' it does work:
select ?property where {
?s ?property ?o.
} limit 1
Why might this be? Shouldn't the engine be able to work this one out quickly
even with 'distinct', as it needs to only traverse a single triple to
compute the result? It seems the engine is doing some unnecessary
computation to do with 'distinct' and is timing out because of it.
Best regards,
Curran
On Tue, May 24, 2011 at 9:17 AM, Kingsley Idehen <[email protected]>wrote:
> On 5/24/11 8:30 AM, Mohamed Morsey wrote:
> > Hi Sarasi,
> >
> > I've performed that query with limit 1000, and it worked on one of our
> > local endpoints, and it ended within 3 minutes.
> > So I guess that the maximum time allowed for a query on the official
> > endpoint is relatively low, but the query itself is executable with
> limit.
> >
> > Hope that helps.
> >
> All,
>
> If we want to have a live DBpedia endpoint that serves the whole world,
> we have to have it configured in such a way that it forces use of OFFSET
> and LIMIT.
>
> We are very experienced with DBMS oriented data exposed to massive
> concurrent users, and this stems to periods prior to the pervasive Web
> of today, thus we've configured the DBpedia SPARQL endpoint with this
> experience in hand.
>
> Once again, the DBpedia endpoint is for everyone, so we deliberately
> protect against inconsiderate use e.g. attempting to get massive results
> sets in single query passes at the expense of others.
>
> Also remember, you can make application or service specific instances of
> the DBpedia SPARQL endpoint via a number of offerings on EC2 if you seek
> hassle free reconstruction of DBpedia.
>
> Links:
>
> 1. http://blog.dbpedia.org/2011/01/31/dbpedia-36-ami-available/ .
>
> --
>
> Regards,
>
> Kingsley Idehen
> President& CEO
> OpenLink Software
> Web: http://www.openlinksw.com
> Weblog: http://www.openlinksw.com/blog/~kidehen
> Twitter/Identi.ca: kidehen
>
>
>
>
>
>
>
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