Hi,
I also found other cases where the results are not correct. For example,
if you try the example query "overall causes of death ranking", there is
no error and a long computation (eating up most of my CPU) and,
eventually, no results.
Cheers,
Markus
On 21.12.2016 11:11, Markus Kroetzsch wrote:
Hi,
Interesting. I encountered some problems in my initial tests though:
(1) The results do not seem to be correct. The example query related to
films returns 55 results, while on the official endpoint it returns 128.
It seems that this is not because of missing data, but because of wrong
multiplicities (the correct result has several rows repeated multiple
times). Is there an implicit DISTINCT applied in this service somewhere?
Are there any other changes from the normal SPARQL semantics?
(2) It is really slow. The sample query took 55s on my machine
(producing only half of the results), while it takes 0.2s on WDQS. I am
afraid that hard queries which would timeout on WDQS might take too long
to be used at all.
However, I would still like to try it with one of our harder queries.
Can I use the service from a program (my harder queries have too many
results to be displayed in a browser -- this is why they are hard ;-)?
Ideally, I would like to use it like a SPARQL service that I send a
request to. Is this possible?
Best,
Markus
On 21.12.2016 09:23, Léa Lacroix wrote:
Hello all,
The SPARQL endpoint we are running at http://query.wikidata.org has
several measures in place in order to ensure it stays up and running and
available for everyone, for example the 30 sec query timeout. This is
necessary but also prevents some useful queries from being run. One way
around this is Linked Data Fragments. It allows for some of the query
computation to be done on the client-side instead of our server.
We have set this up now for testing and would appreciate your testing
and feedback. You can find out more about Linked Data Fragments
<http://linkeddatafragments.org/concept/> and documentation for our
installation
<https://www.mediawiki.org/wiki/Wikidata_query_service/User_Manual#Linked_Data_Fragments_endpoint>.
Also, you can see a demo of client-side SPARQL evaluation and LDF server
usage here: http://ldfclient.wmflabs.org/
Please note - it's in no way a production service for anything, just a
proof-of-concept deployment of LDF client. If you like how it works, you
can get it from the source
<https://github.com/LinkedDataFragments/jQuery-Widget.js> and deploy it
on your own setup.
Feel free to ask Stas (Smalyshev (WMF)) for any further question!
--
Léa Lacroix
Community Communication Manager for Wikidata
Wikimedia Deutschland e.V.
Tempelhofer Ufer 23-24
10963 Berlin
www.wikimedia.de <http://www.wikimedia.de>
Wikimedia Deutschland - Gesellschaft zur Förderung Freien Wissens e. V.
Eingetragen im Vereinsregister des Amtsgerichts Berlin-Charlottenburg
unter der Nummer 23855 Nz. Als gemeinnützig anerkannt durch das
Finanzamt für Körperschaften I Berlin, Steuernummer 27/029/42207.
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