CREATE SERVER fuseki
FOREIGN DATA WRAPPER rdf_fdw 
OPTIONS (
  endpoint   'http://fuseki:3030/dt/sparql',
  update_url 'http://fuseki:3030/dt/update',
  http_proxy 'http://172.19.42.100:3128',
  connect_timeout '1');
CREATE FOREIGN TABLE ft (
  subject   rdfnode OPTIONS (variable '?s'),
  predicate rdfnode OPTIONS (variable '?p'),
  object    rdfnode OPTIONS (variable '?o') 
)
SERVER fuseki OPTIONS (
  log_sparql 'true',
  sparql 'SELECT * WHERE {?s ?p ?o}',
  sparql_update_pattern '?s ?p ?o .'
);
CREATE USER MAPPING FOR postgres
SERVER fuseki OPTIONS (user 'admin', password 'secret');
/* Correct proxy settings */
INSERT INTO ft (subject, predicate, object)
VALUES  ('<https://www.uni-muenster.de>', '<http://dbpedia.org/property/name>', '"Westfälische Wilhelms-Universität Münster"@de');
INFO:  SPARQL query sent to 'fuseki':
INSERT DATA { <https://www.uni-muenster.de> <http://dbpedia.org/property/name> "Westfälische Wilhelms-Universität Münster"@de };


SELECT * FROM ft;
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}

INFO:  SPARQL returned 1 record.

            subject            |             predicate              |                     object                     
-------------------------------+------------------------------------+------------------------------------------------
 <https://www.uni-muenster.de> | <http://dbpedia.org/property/name> | "Westfälische Wilhelms-Universität Münster"@de
(1 row)

SELECT *
FROM sparql.describe('fuseki', 'DESCRIBE <https://www.uni-muenster.de>');
            subject            |             predicate              |                     object                     
-------------------------------+------------------------------------+------------------------------------------------
 <https://www.uni-muenster.de> | <http://dbpedia.org/property/name> | "Westfälische Wilhelms-Universität Münster"@de
(1 row)

CALL rdf_fdw_clone_table(
        create_table => true,
        foreign_table => 'public.ft',
        target_table  => 'public.t1'
     );
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}
ORDER BY ASC(?s) 
OFFSET 0 LIMIT 100

INFO:  SPARQL returned 1 record.

INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}
ORDER BY ASC(?s) 
OFFSET 100 LIMIT 100

INFO:  SPARQL returned 0 records.

SELECT * FROM public.t1;
            subject            |             predicate              |                     object                     
-------------------------------+------------------------------------+------------------------------------------------
 <https://www.uni-muenster.de> | <http://dbpedia.org/property/name> | "Westfälische Wilhelms-Universität Münster"@de
(1 row)

UPDATE ft SET object = '"University of Münster"@en'
WHERE subject = '<https://www.uni-muenster.de>';
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o
 ## rdf_fdw pushdown conditions ##
 FILTER(?s = <https://www.uni-muenster.de>)
}

INFO:  SPARQL returned 1 record.

INFO:  SPARQL query sent to 'fuseki':
DELETE DATA { <https://www.uni-muenster.de> <http://dbpedia.org/property/name> "Westfälische Wilhelms-Universität Münster"@de };
INSERT DATA { <https://www.uni-muenster.de> <http://dbpedia.org/property/name> "University of Münster"@en };


SELECT * FROM ft;
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}

INFO:  SPARQL returned 1 record.

            subject            |             predicate              |           object           
-------------------------------+------------------------------------+----------------------------
 <https://www.uni-muenster.de> | <http://dbpedia.org/property/name> | "University of Münster"@en
(1 row)

DELETE FROM ft;
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}

INFO:  SPARQL returned 1 record.

INFO:  SPARQL query sent to 'fuseki':
DELETE DATA { <https://www.uni-muenster.de> <http://dbpedia.org/property/name> "University of Münster"@en };


SELECT * FROM ft;
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}

INFO:  SPARQL returned 0 records.

 subject | predicate | object 
---------+-----------+--------
(0 rows)

/* Wrong proxy url - must fail */
ALTER SERVER fuseki OPTIONS (SET http_proxy 'http://172.19.42.100:250');
SELECT * FROM ft;
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}

WARNING:  ExecuteSPARQL: request to 'fuseki' failed (1)
WARNING:  ExecuteSPARQL: request to 'fuseki' failed (2)
WARNING:  ExecuteSPARQL: request to 'fuseki' failed (3)
ERROR:  unable to connect to 'fuseki'
DETAIL:  Could not connect to server (curl error code 7)
SELECT * FROM sparql.describe('fuseki', 'DESCRIBE <https://www.uni-muenster.de>');
WARNING:  ExecuteSPARQL: request to 'fuseki' failed (1)
WARNING:  ExecuteSPARQL: request to 'fuseki' failed (2)
WARNING:  ExecuteSPARQL: request to 'fuseki' failed (3)
ERROR:  unable to connect to 'fuseki'
DETAIL:  Could not connect to server (curl error code 7)
CALL rdf_fdw_clone_table(
        foreign_table => 'public.ft',
        target_table  => 'public.t1'
     );
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?p ?o 
{?s ?p ?o}
ORDER BY ASC(?s) 
OFFSET 0 LIMIT 100

WARNING:  ExecuteSPARQL: request to 'fuseki' failed (1)
WARNING:  ExecuteSPARQL: request to 'fuseki' failed (2)
WARNING:  ExecuteSPARQL: request to 'fuseki' failed (3)
ERROR:  unable to connect to 'fuseki'
DETAIL:  Could not connect to server (curl error code 7)
/* Cleanup */
DROP TABLE public.t1;
DROP SERVER fuseki CASCADE;
NOTICE:  drop cascades to 2 other objects
DETAIL:  drop cascades to foreign table ft
drop cascades to user mapping for postgres on server fuseki