Wikidata query for items with one Wikipedia page not in English - sparql

Question

I want to find Wikidata items, with each referring to exactly one Wikipedia page which is not an en. Wikipedia page.
I came up with this query:
SELECT ?item WHERE {
?article schema:about ?item .
FILTER (SUBSTR(str(?article), 9, 2) != "en") .
{
SELECT ?item (COUNT(DISTINCT ?lang) AS ?count) WHERE {
?item wdt:P1367 ?yp_id . # BBC 'Your paintings' artist identifier
?article schema:about ?item .
FILTER (SUBSTR(str(?article), 11, 15) = ".wikipedia.org/") .
?article schema:inLanguage ?lang .
} GROUP BY ?item
HAVING (?count=1)
ORDER BY DESC (?count)
}
}
It executes. However, I always get a timeout.
Is there a better query to achieve what I am looking for?

Answer 1

Here's some tip:
Since you take only ?count=1, there is no reason to order by ?count.
Since for each article you can have only one ?lang, you can count by ?article without considering a redundant variable.
Instead of working on (sub)strings, just use the schema:isPartOf property for selecting the specific domain that you want to exclude.
Use FILTER NOT EXISTS instead of FILTER (... != ...)
The fourth optimiziation is the most important and it is sufficient per se.
SELECT ?item WHERE {
FILTER NOT EXISTS {
?article schema:about ?item ;
schema:isPartOf <https://en.wikipedia.org/> .
}
{
SELECT ?item (COUNT(DISTINCT ?article) AS ?count) WHERE {
?item wdt:P1367 ?yp_id . # BBC 'Your paintings' artist identifier
?article schema:about ?item .
FILTER (SUBSTR(str(?article), 11, 15) = ".wikipedia.org/") .
}
GROUP BY ?item
HAVING (?count=1)
}
}