Path query for taxons times out
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	Smalyshev
	Sep 16 2016, 9:08 PM

Description

This query:

SELECT ?item ?taxonName ?taxonRank ?parentName ?parentRank ?higherParent WHERE {
  BIND("Rivasmartinezia" AS ?taxonName) .
  BIND(wd:Q34740 AS ?taxonRank) . # Genus
  BIND(wd:Q756 AS ?higherParent) . # Plantae
  ?item wdt:P225 ?taxonName .
  ?item wdt:P105 ?taxonRank .
  ?item wdt:P171/wdt:P225 ?parentName .
  ?item wdt:P171/wdt:P105 ?parentRank .
  ?item (wdt:P171)* ?higherParent .
}

Times out even though it has only one match for ?item (wd:Q26902704) and this:

ASK {
  BIND(wd:Q756 AS ?higherParent) . # Plantae
  wd:Q26902704 (wdt:P171)+ ?higherParent .
}

is fast.

See: https://www.wikidata.org/wiki/Wikidata:Contact_the_development_team#SPARQL:_.28wdt:P171.29.2A

Event Timeline

Smalyshev created this task.Sep 16 2016, 9:08 PM

Restricted Application added projects: Wikidata, Discovery-ARCHIVED. · View Herald TranscriptSep 16 2016, 9:08 PM

Restricted Application added a subscriber: Aklapper. · View Herald Transcript

Smalyshev renamed this task from path query times out to Path query for taxons times out.Sep 16 2016, 11:35 PM

Smalyshev moved this task from Incoming to Blazegraph on the Wikidata-Query-Service board.

Smalyshev moved this task from Needs triage to WDQS on the Discovery-ARCHIVED board.Sep 20 2016, 7:10 PM

Smalyshev added a project: Upstream.Dec 15 2016, 10:56 PM

Lydia_Pintscher moved this task from incoming to monitoring on the Wikidata board.Dec 16 2016, 9:59 AM

This one works now:

SELECT ?item ?taxonName ?taxonRank ?parentName ?parentRank ?higherParent WHERE {
  BIND("Rivasmartinezia" AS ?taxonName) .
  BIND(wd:Q34740 AS ?taxonRank) . # Genus
  BIND(wd:Q756 AS ?higherParent) . # Plantae
  ?item wdt:P225 ?taxonName .
  ?item wdt:P105 ?taxonRank .
  ?item wdt:P171/wdt:P225 ?parentName .
  ?item wdt:P171/wdt:P105 ?parentRank .
  ?item (wdt:P171)* ?higherParent .
  hint:Prior hint:gearing "forward" .
}

(note the hint). The hint allows to control in which direction the path is traversed.
See also https://wiki.blazegraph.com/wiki/index.php/QueryHints

Since this is probably the only solution for this now (it's very hard to make optimizer always guess correctly which way to go) and upstream ticket is considered resolved for now, I'm resolving this too.

Path query for taxons times outClosed, ResolvedPublicActions

Description

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Path query for taxons times out
Closed, ResolvedPublic
Actions