Hi Patrick,
> On 8 Oct 2015, at 13:33, Patrick van Kleef <pkl...@openlinksw.com> wrote:
>
>> I know i can do something like the following, but it's terribly slow
>> (timeout, no result):
>>
>> select * where {
>> ?s rdfs:label ?l .
>> FILTER(str(?l) = "贝拉克·奥巴马").
>> }
>>
>> [...]
>
> This of course would result in a partial table scan as the str function would
> need to be evaluated for each record.
yes and no... i mean the current implementation seems to, but it could
certainly be optimised, as this sadly is the default pattern to search across
languages :(
>> [...]
>
> The problem is that when you use the contain function with unicode characters
> it has difficulties find word separation, so you need to quote the word
> yourself:
>
> Try like this:
>
> prefix dbpedia: <http://dbpedia.org/resource/>
> select * where {
> ?s rdfs:label ?l .
> FILTER(bif:contains(?l, "'贝拉克·奥巴马'")).
> }
>
> which will give you super fast results:
> [...]
Cool, thanks, with this i can at least make it work somehow. Sadly it's still
not exactly what i need...
for example if i search for an exact label "Barack Obama" this method will give
me way too many results:
select * where {
?s rdfs:label ?l .
FILTER(bif:contains(?l, "'Barack Obama'")).
}
http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&qtxt=prefix+dbpedia%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fresource%2F%3E%0D%0Aselect+*+where+{%0D%0A++%3Fs+rdfs%3Alabel+%3Fl+.%0D%0A++FILTER%28bif%3Acontains%28%3Fl%2C+%22%27Barack+Obama%27%22%29%29.%0D%0A}&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on
I'd actually only be interested in exact matches, so the equivalent of `?s
rdfs:label ?l . FILTER(str(?l) = "Barack Obama")`, just performant ;)
The workaround i found for now is this:
select * where {
?s rdfs:label ?l .
FILTER(bif:contains(?l, "'Barack Obama'") && str(?l) = "Barack Obama").
}
http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&qtxt=prefix+dbpedia%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fresource%2F%3E%0D%0Aselect+*+where+{%0D%0A++%3Fs+rdfs%3Alabel+%3Fl+.%0D%0A++FILTER%28bif%3Acontains%28%3Fl%2C+%22%27Barack+Obama%27%22%29+%26%26+str%28%3Fl%29+%3D+%22Barack+Obama%22%29.%0D%0A}&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on
but is that the "best" way?
Best,
Jörn
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