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SPARQL query optimization. [Estimated execution time exceeds the limit of 1500 (sec)]

I am trying to run this request http://dbpedia.org/sparql , but I am getting an error that my request is too expensive. When I run the query through http://dbpedia.org/snorql/ , I get:

The estimated execution time 25012730 (sec) exceeds the limit of 1500 (sec) ...

When I execute a query through my python script using SPARQLWrapper, I just get HTTP 500.

I believe that I need to do something to optimize my SPARQL query. I need data to iterate through educational institutions and import them into a local database, maybe I'm using SPARQL incorrectly and should do it in a fundamentally different way.

Hope someone can help me!

Inquiry

PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX : <http://dbpedia.org/resource/>
PREFIX dbpedia2: <http://dbpedia.org/property/>
PREFIX dbpedia: <http://dbpedia.org/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>

            SELECT DISTINCT ?uri
                ?name
                ?homepage
                ?student_count
                ?native_name
                ?city
                ?country
                ?type
                ?lat ?long
                ?image

            WHERE {
                ?uri rdf:type dbpedia-owl:EducationalInstitution .
                ?uri foaf:name ?name .
                OPTIONAL { ?uri foaf:homepage ?homepage } .
                OPTIONAL { ?uri dbpedia-owl:numberOfStudents ?student_count } .
                OPTIONAL { ?uri dbpprop:nativeName ?native_name } .
                OPTIONAL { ?uri dbpprop:city ?city } .
                OPTIONAL { ?uri dbpprop:country ?country } .
                OPTIONAL { ?uri dbpprop:type ?type } .
                OPTIONAL { ?uri geo:lat ?lat . ?uri geo:long ?long } .
                OPTIONAL { ?uri foaf:depiction ?image } .
            }
            ORDER BY ?uri
            LIMIT 20 OFFSET 10
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3

. dbpedia SPARQL. .

, - :

 SELECT DISTINCT ?uri WHERE {
                ?uri rdf:type dbpedia-owl:EducationalInstitution .
                ?uri foaf:name ?name .
 } ORDER BY ?uri
 LIMIT 20 OFFSET 10

dbpedia-owl:EducationalInstitution, ... ( ):

        SELECT DISTINCT ?uri
            ?name
            ?homepage
            ?student_count
            ?native_name
            ?city
            ?country
            ?type
            ?lat ?long
            ?image

        WHERE {
            ?uri rdf:type dbpedia-owl:EducationalInstitution .
            ?uri foaf:name ?name .
            OPTIONAL { ?uri foaf:homepage ?homepage } .
            OPTIONAL { ?uri dbpedia-owl:numberOfStudents ?student_count } .
            OPTIONAL { ?uri dbpprop:nativeName ?native_name } .
            OPTIONAL { ?uri dbpprop:city ?city } .
            OPTIONAL { ?uri dbpprop:country ?country } .
            OPTIONAL { ?uri dbpprop:type ?type } .
            OPTIONAL { ?uri geo:lat ?lat . ?uri geo:long ?long } .
            OPTIONAL { ?uri foaf:depiction ?image } .
        FILTER (?uri = <http://dbpedia.org/resource/%C3%89cole_%C3%A9l%C3%A9mentaire_Marie-Curie>)
        }

<http://dbpedia.org/resource/%C3%89cole_%C3%A9l%C3%A9mentaire_Marie-Curie> .

... , , -. . - , dbpedia SPARQL.

+3

! LIMIT OFFSET .

LIMIT 50 , , , , . , , OFFSET, , .

SELECT * WHERE { ... } LIMIT 100
SELECT * WHERE { ... } LIMIT 100 OFFSET 100
...
+2

URI (, ), URI where ( , ), URI FILTER.

, :

WHERE { <http:/...> ... }


WHERE { ?uri .... FILTER (?uri...)

I also found that UNION is faster than filters designed to match multiple resources.

Just because we do SPARQL, this does not mean that we can forget the nightmares of SQL tuning, welcome to the wonderful world of SPARQL tuning! :)

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