Hi,
SQID uses a somewhat challenging SPARQL query to refresh its statistical
data for the current usage of classes [1]. This is done once per hour,
with one retry after 60sec if the first attempt times out. In the past,
timeouts have been common, but it usually worked after a while.
Since a few days, however, the query always times out. In spite of the
48 attempts throughout each day, the query did not succeed once since
8/30/2016, 8:12:28 PM [2].
Possible explanations:
* WDQS experiences more load now (every day, every hour).
* The query got slower since for some reason the overall number of P31
statements increased in a sudden way (or for some reason crossed some
threshold).
* There have been technical changes to WDQS that reduce performance.
I don't have statistics on the success rate of the problematic query in
past weeks, so I cannot say if the timeout rate had increased before the
current week.
Does anybody have further information or obsevations that could help to
clarify what is going on? We can rewrite our software to use simpler
queries if this one fails now, but it seems like a step backwards.
Best regards,
Markus
[1] Here is the query:
SELECT ?cl ?clLabel ?c WHERE {
{ SELECT ?cl (count(*) as ?c) WHERE { ?i wdt:P31 ?cl } GROUP BY ?cl }
SERVICE wikibase:label {
bd:serviceParam wikibase:language "en" .
}
}
[2]
https://tools.wmflabs.org/sqid/#/status
--
Prof. Dr. Markus Kroetzsch
Knowledge-Based Systems Group
Faculty of Computer Science
TU Dresden
+49 351 463 38486
https://iccl.inf.tu-dresden.de/web/KBS/en