The issue is with the
"SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }", which
seems to be a very expensive operation.
When you change the query to its more basic form:
SELECT ?item ?itemLabel
WHERE
{
?item wdt:P31 [] ;
rdfs:label ?itemLabel .
FILTER (lang(?itemLabel) = "en")
} LIMIT 10
the results seems to be in before you hit enter.
I am a big fan of the "SERVICE wikibase:label { bd:serviceParam
wikibase:language
"en". }" due to is ease, but as said it is so expensive, that getting rid
of it is one of the first things I do when a query times out.
On Sun, Nov 25, 2018 at 3:11 PM Gerard Meijssen <[email protected]>
wrote:
> At that, a Reasonator page fails to load eg
> https://tools.wmflabs.org/reasonator/?q=Q57328736&lang=en I have noticed
> that using tools like SourceMD will not always show the labels for items
> that were processed (less than 20)...
>
> Performance is getting worse and particularly when you rely on up to date
> information, Wikidata is not what we were used to.
> Thanks,
> GerardM
>
> On Sun, 25 Nov 2018 at 14:56, Markus Kroetzsch <
> [email protected]> wrote:
>
>> Hi,
>>
>> I just noticed that BlazeGraph takes an undue amount of time for a
>> rather simple type of queries. The following times out:
>>
>> SELECT ?item ?itemLabel
>> WHERE
>> {
>> ?item wdt:P31 []
>> SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
>> } LIMIT 10
>>
>> Manually forcing a specific query plan makes the query work in <200ms:
>>
>> SELECT ?item ?itemLabel
>> WHERE
>> {
>> { SELECT * WHERE { ?item wdt:P31 [] } LIMIT 10 }
>> SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
>> }
>>
>> But of course the original query should normally be streaming and not
>> depend on any such smartness to push LIMIT inwards.
>>
>> Cheers,
>>
>> Markus
>>
>>
>> _______________________________________________
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>> [email protected]
>> https://lists.wikimedia.org/mailman/listinfo/wikidata
>>
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