On 29.04.2015 20:56, Luca Martinelli wrote:
Dear all,
I need to know about the possibility of making queries on a Wikibase
instance. I think it is possible to make queries on data on a
particular instance only with external tools at the moment, right?
Yes, this is correct. The SPARQL query support that we currently offer
is obtained by making an RDF export and loading it into a SPARQL
database (we use Virtuoso but you could also use BlazeGraph, for
example; both have free and open source versions and are not hard to
install overall; if your data is not so large, you could also try Jena;
there are further open source RDF databases, but these are the most
prominent right now I think).
The RDF export, too, is not currently generated by Wikibase. However,
Wikidata Toolkit, which we use to make the RDF dumps, can be used with
data from any Wikibase installation in theory. In practice, nobody has
asked for this yet and we might have to make a few adjustments to really
get it to work in a convenient way. For a start, I don't know what kind
of export options a standalone Wikibase offers you at the moment. We can
use the usual XML-based page dump if it contains valid JSON for a change
(this was not the case for Wikidata last time I checked ...). Better yet
would be the JSON exports, but I don't know if you can generate them
with vanilla Wikibase or if WMF is using some special tools for this.
Anyway, it can't be too hard to make this work and once it is done you
would have a query service that is at the same level as the one of
Wikidata. You could even combine data from more than one Wiki in one RDF
database, e.g., to run queries over data from both.
Regards,
Markus
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