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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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Is "Enhanced VPC routing" needed for federated query if redshift and RDS both reside in same VPC?

Is it necessary for redshift to enable "Enhanced VPC routing" and "Publicly accessible" in order to run federated queries? Basically in redshift, I want to run some SQL queries which joins few tables from RDS-postgres residing in the same VPC.
Gsb
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federated query in GCP big query with schema not working

I am doing a POC to use bigquery's federated query feature. I have a Cloud Sql postgresql db. All tables are part of app schema. When I write a query like this it doesn't work. SELECT * FROM EXTERNAL_QUERY("xxxx.us.xxxx", "SELECT * FROM…
Sandeep Parmar
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Google Cloud BQ error: Invalid table-valued function EXTERNAL_QUERY Failed to get query schema from MySQL server

I have an external connection set up on Google Big Cloud and trying to use Federated Queries to mysql instance. I can successfully run a query against the information schema like this: SELECT * FROM EXTERNAL_QUERY("xxxxxxx", "SELECT * FROM…
Tirso Martinez
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Symfony and MySQL: read/write on different databases on different MySQL servers

I have a PHP project written in Symfony that is using connection on different databases. An example is a users table on one DB and another related table on another DB. This works well except that I am planning to move one of the two MySQL DBs to…
Milos Cuculovic
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AWS Neptune FTS returns IOException on every federated queries to OpenSearch

I am trying to implement full text search on AWS Neptune (engine 1.0.4.2) with AWS OpenSearch. A GET amazon_neptune/_search on OpenSearch returns: { "took": 5, "timed_out": false, "_shards": { "total": 2, "successful": 2, …
realpac
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Redshift permission denied on Federated Table

I am trying to query a Federated Table in Redshift with a user different from the one who created the Federated Schema and Table. Of course I get a permission denied for relation my_federated_table so it is the case to grant the right…
Vzzarr
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Redshift Federated Query error: timeout expired code: 2500

After having created a 'Federated Schema' to access a remote RDS instance (different AWS account but VPC Peered): CREATE EXTERNAL SCHEMA federated_schema FROM POSTGRES DATABASE 'popstgres_db' SCHEMA 'public' URI 'my.host.com' IAM_ROLE…
Vzzarr
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How to add a SERVICE clause to SelectBuilder using Apache Jena's query builder?

I’m using the Jena query builder from the Jena-extras and I was wondering if there was a way to add a SERVICE clause to a SelectBuilder object. My code right now looks like this: SelectBuilder builder = new SelectBuilder() .addPrefix( "rdf",…
jDeJong
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How to read every file in a Google Storage bucket from BigQuery and create one table for each file in the bucket?

I have a bucket that has 28 files and I would like to load them in different tables (one table per file in the bucket). Each file in the bucket looks like this: file_1_2020.csv file_2_2020.csv .. file_28_2020.csv I would like that the table had the…
Pedro Pablo Severin Honorato
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GraphDB - Federated Query

I would like to know how to perform a federated search on GraphDB. For example, to insert the code below in GraphDB, how should I do it? The idea is to add the content below to my local GraphDB. #Locations of air accidents in wikidata -…
João
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SPARQL endpoints and GraphDB

I am a student and I'm learning to use sparql. I would like to query an endpoint by running the sparql query from GRAPHDB. So looking online I found that the solution is to use SERVICE with the endpoint link. I have tried with the wikidata endpoint…
Luca Squadrone
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AWS Athena comes with Athena Federated Query

I am going through with AWS Athena Federated Query page and got to know "you can use Athena Federated Query (Preview) to query the data in place or build pipelines that extract data from multiple data sources and store them in Amazon S3." If I…
Amit Dass
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SERVICE against Virtuoso DBPedia Gives "Virtuoso S0022 Error SQ200 : No Column"

I run a SPARQL query in a local GraphDB triplestore that contains a SERVICE clause that goes to DBPedia Virtuoso. The query basically fetches labels of some DBPedia URIs directly from DBPedia (note the subquery executed first to fetch local results,…
ThomasFrancart
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Graphdb sparql cannot make federated query

I am trying to make a federated query using my local GraphDB database and SPARQL endpoint. For some reason I always get errors or empty columns in my result table. I tried several SPARQL endpoints which are working perfectly fine on FactForge. My…
dogu
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Federated SPARQL query in dbpedia and wikidata: Few questions

I have following query: # endpoint used: https://query.wikidata.org/ # # PREFIX wd: # PREFIX wdt: PREFIX dbo: PREFIX dbp:…
RoRu
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