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Questions tagged [federated-queries]

Federated query is the SPARQL 1.1 ability to take a query and provide solutions based on information from many different sources. The SERVICE keyword instructs a query processor to invoke a portion of a SPARQL query against a remote SPARQL endpoint.

Specification

Federated queries on public endpoints

  • DBpedia does not allow federated queries [1];
  • Wikidata allows federated queries to a selected number of external endpoints [2].
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How to make, in one SPARQL query, three independent queries on three different SPARQL endpoints?

is there a way that I can do three independent queries on on three different SPARQL endpoints, in one SPARQL query? For example, I have three SPARQL endpoints (i.e., url1, url2 and url3) and three independent queries I want to make, i.e., query1 on…
Artemis1216
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SPARQL Federated Query Not Returning All Solutions

This is an evolution of this question. Basically I am having trouble getting all the solutions to a SPARQL query from a remote endpoint. I have read through section 2.4 here because it seems to describe a situation almost identical to mine. The…
Evan
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How can I match string labels from an external SPARQL endpoint with string labels in my local ontology?

PREFIX ex: PREFIX dbo: SELECT ?name (STR(?name) AS ?strip_name) ?name2 WHERE { ?p ex:displayName ?name2 . SERVICE { { ?s…
Evan
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SPARQL - Insert data from remote endpoint

How can i query a remote endpoint (like endpoints of DBPedia or Wikidata) and insert resulting triples in a local graph? So far, i know that there are commands like INSERT, ADD, COPY etc. which can be used for such tasks. What i don't understand is…
nichoio
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SPARQL: Federated query gives no result when using local file, while same query on dbpedia does

the local file uploaded on stardog: @prefix dbo: . @prefix dbr: . dbr:United_States dbo:leader dbr:John_Roberts , dbr:Joe_Biden , dbr:Barack_Obama , dbr:Paul_Ryan…
Jerry
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SPARQL federated query "SERVICE" returns Virtuoso RDFZZ Error: unexpected variable name 'stubvar14'

I want to get a list of Persons from two different SPARQL-Endpoints, so I'm using this query on de.dbpedia: PREFIX category-en: SELECT distinct * WHERE { ?name dcterms:subject…
fobi
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Make jena and fuseki proxy aware for federated queries

Our application is built on top of Jena and Fuseki. The application uses federated SPARQL queries accessing SPARQL endpoints in the public domain. Some networks which the application is intended for only allow HTTP requests via a HTTP proxy as part…
marqh
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Sparql howto select one result to ask another service in federated search

How I can select one of rdf possible labels to send it to the Federated Search? I have a rdf record who has several links to another databases:
jordi Pallares
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Asking federated SPARQL queries with SPARQLWrapper

How can we ask federated queries using SPARQLWrapper? If it is not possible, is there any alternate library available for making such queries for Python?
imran
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Federated dbpedia query timeouts with offset > 1000

At this endpoint http://spcdata.digitpa.gov.it:8899/sparql I have a list of all italian municipalities. I want to fetch the population data for every muncipality from dbpedia, and I'm using the owl:sameAs property as a pointer to dbpedia . In this…
Dev-otchka
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Redshift cross cluster insert

I need to insert data into a table from one redshift cluster to another. I have it working by injecting one of my postgres rds in the middle. Use postgres_fdw on the rds to point to the table i want to insert on in Cluser B Use federated queries on…
user433342
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federated mysql query with a reserved word column name fails to run in Redhsift

I have a remote connection into a mysql database from Redshift. Mysql table has a column year_month which is a reserved word in mysql and since this table is already populated and applications are using it, column name cannot be changed. I tried…
Shanthi
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Redshift federated query to RDS (MySQL) when encryption is not enabled

I'm trying to run a federated redshift query on a schema tied to an RDS instance (data encrypted at REST, but the connection doesn't require SSL encrpytion. For any query I send, I get this error: Connection to remote MySQL server was not…
Gadjo Bytes
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How do you run a federated query in Google BigQuery using the Google.Apis.Bigquery.v2 and C#?

I have a working .netcore console app written in C# that can run pretty much every example shown here: Google .Net client library For example, this code runs perfectly fine: BigQueryClient client = BigQueryClient.Create(projectId); string sql…
A. Acevedo
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Redshift Spectrum vs Federated Query

Amazon Redshift Spectrum - allows you to ONLY query data on S3 Amazon Redshift Federated Query - allows you to query data on other databases and ALSO S3. So, if we are querying S3, the query we execute is exactly same in both cases: Select * from…
Jasper2000
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