I'm finding that I occasionally get responses missing parts from the WDQS with queries like this:
SELECT ?statusLabel ?sitelink WHERE {
?item wdt:P141 ?status.
{ ?item rdfs:label "Leptailurus serval"@en } UNION { ?item skos:altLabel "Leptailurus serval"@en }
OPTIONAL { ?sitelink schema:about ?item .
?sitelink schema:isPartOf <https://en.wikipedia.org/> .
}
SERVICE wikibase:label {bd:serviceParam wikibase:language "en" .}
}Where if I run the query repeatedly I occasionally get it failing to match the ?sitelink variable (with the same string).
I think this happens when I get loadbalanced to wdqs1002 which is currently missing around 25M triples. See. https://grafana.wikimedia.org/dashboard/db/wikidata-query-service