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WDQS fails to deliver all subclasses of Gene (Q7187)
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Description

WDQS fails to deliver all subclasses of Gene (Q7187)

PREFIX wd: <http://www.wikidata.org/entity/> 
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
SELECT ?subClass WHERE {
   ?subClass wdt:P279/wdt:P279* wd:Q7187 .
   }

Outcome: SERVER ERROR.

It provides nicely for any other WDCM semantic class.

Event Timeline

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptAug 28 2018, 1:05 PM
PREFIX wd: <http://www.wikidata.org/entity/> 
PREFIX wdt: <http://www.wikidata.org/prop/direct/> 
SELECT ?item WHERE {?item (wdt:P31|(wdt:P31/wdt:P279*)) wd:Q7187.  }

SERVER ERROR.

Could somebody please advise? This worked until September.

Smalyshev closed this task as Resolved.Sep 4 2018, 7:53 PM
Smalyshev claimed this task.

Looks like this query times out. Try using BFS, like this:

SELECT ?subClass WHERE {
  SERVICE gas:service {
     gas:program gas:gasClass "com.bigdata.rdf.graph.analytics.BFS" .
     gas:program gas:in wd:Q7187 .
     gas:program gas:out ?subClass .
     gas:program gas:linkType wdt:P279 .
     gas:program gas:traversalDirection "Reverse" .
  }
}

Given that there are over 500K results, timeout is not surprising.

Side note: some timeouts can produce partial results if the timing is just right (wrong). Looks like depending on browser and protocol, it may be very hard for the GUI to detect what happened in that case (all it gets is "something wrong happened with the request") so you get a generic "Server Error" message. The usual clue is if it takes around a minute and it's "Server Error" then it's almost certainly timeout with partial result.

GoranSMilovanovic reopened this task as Open.Sep 4 2018, 8:38 PM

@Smalyshev I have reopened the task to say: thank you.

Also, in T202988#4557700 you were right on the observation of my main concern: namely, it was not reported as a timeout - rather as a server error. I have to admit that I've been confused.

Finally, please: I don't like running SPARQL queries that I do not understand fully. I've found out the following documentation: https://www.mediawiki.org/wiki/Wikidata_Query_Service/Categories. Could you please advise on any other place where I could learn more about gas:service? Again, thanks a lot.

Smalyshev closed this task as Resolved.Sep 4 2018, 8:44 PM

gas:service is a Blazegraph extension documented here: https://wiki.blazegraph.com/wiki/index.php/RDF_GAS_API

There's also a User Manual: https://www.mediawiki.org/wiki/Wikidata_Query_Service/User_Manual but it does not document these things, only refers to them, using the original docs is the best way now.

Partial results issues are tracked as T169666: Render partial results.

@Smalyshev Once again: thanks a lot!
@Lydia_Pintscher: thank you for your support!