Fuzzy entity query in Wikidata with Sparql times out

问题

I'm trying to do a fuzzy (ie.. partial or case-insensitive) entity label lookup in Wikidata with Sparql (via the online endpoint). Unfortunately these return a "QueryTimeoutException: Query deadline is expired." I'm assuming this is because the query is returning too many results to run through the filter in Wikidata's 1 minute timeout.

Here's the specific query:

def findByFuzzyLabel(self, item_label):
    qstring = '''
        SELECT ?item WHERE {
            ?item rdfs:label ?label .
            FILTER( lcase(str(?label)) = "%s")
        }
        LIMIT 20
        ''' % (item_label)
    results = self.query(qstring)

Is there a way to do a partial string and/or case-insensitive label lookup on Wikidata's entity labels or will I need to do this offline on a download of raw data?

I'm looking to match labels such as "Lindbergh" to "Charles Lindbergh" and also handle case insensitivity in some instances. Any suggestions how to do this, whether via Sparql or offline in Python are appreciated.

回答1:

Be more specific. Triplestores work with things, not with strings. For example, the following query works fine:

SELECT ?item WHERE {
    ?item wdt:P735 wd:Q2958359 .
    ?item rdfs:label ?label .
    FILTER (CONTAINS(LCASE(STR(?label)), "lindbergh"))
}

If it is not possible to be sufficiently specific, you need full-text search capabilities.

In fact, Blazegraph supports full-text search using magic bds:search predicate, but this facility is not enabled on Wikidata.
Additionally, Blazegraph supports external full-text search using magic fts:search predicate. The current implementation supports Apache Solr only. Perhaps it is relatively easy to support ElasticSearch, which is used in Wikidata, but anyway, this facility is not enabled.

There is a task to provide full-text search in a form of yet another Wikidata magic service, but this functionality is still not available on the public endpoint.

As a workaround, one can use SQL queries on Quarry. This is my query on Quarry:

USE wikidatawiki_p; 
DESCRIBE wb_terms;

SELECT CONCAT("Q", term_entity_id) AS wikidata_id, term_language, term_text, term_search_key
FROM wb_terms
WHERE term_type = 'label' AND
                         term_search_key IN (LOWER('Lindbergh'), LOWER('Charles Lindbergh'));

The query time limit on Quarry is 30 minutes.

回答2:

You can do this online if you change your filter to use the "contains" function.

Example:

 SELECT ?item WHERE {
            ?item rdfs:label ?label .
            FILTER( contains(lcase(?label), 'arles lin' ))
 }
 LIMIT 20

Reference: contains is listed as one of the XPath functions you can use in SPARQL. See: https://www.w3.org/2009/sparql/wiki/Feature:FunctionLibrary#XQuery_1.0_and_XPath_2.0_Functions_and_Operators

Example 2: (with more triples to optimise results)

PREFIX skos: <http://www.w3.org/2004/02/skos/core#Concept>
SELECT ?item  ?label WHERE {
            ?item rdfs:label ?label .
            ?item rdf:type dbo:Person   #Works with our without this too, also try skos:Category
            FILTER( contains(lcase(?label), 'arles lin' ) && LANGMATCHES(LANG(?label), "en")) 
 }
 LIMIT 20

回答3:

You can now use the MediaWiki API directly from SPARQL, using a Wikidata magic service as documented here.

Example :

SELECT * WHERE {
  SERVICE wikibase:mwapi {
      bd:serviceParam wikibase:api "EntitySearch" .
      bd:serviceParam wikibase:endpoint "www.wikidata.org" .
      bd:serviceParam mwapi:search "cheese" .
      bd:serviceParam mwapi:language "en" .
      ?item wikibase:apiOutputItem mwapi:item .
      ?num wikibase:apiOrdinal true .
  }
  ?item (wdt:P279|wdt:P31) ?type
} ORDER BY ASC(?num) LIMIT 20

来源：https://stackoverflow.com/questions/44999328/fuzzy-entity-query-in-wikidata-with-sparql-times-out

标签

sparql

wikidata