\pset null '(null)'
CREATE SERVER fuseki
FOREIGN DATA WRAPPER rdf_fdw 
OPTIONS (
  endpoint   'http://fuseki:3030/dt/sparql',
  update_url 'http://fuseki:3030/dt/update');
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');
INSERT INTO ft VALUES (
  '<http://example.org/s>',
  '<http://example.org/p>',
  '"x"@en } ; INSERT DATA { <http://example.org/pwned> <http://example.org/pwned> <http://example.org/pwned> } ; INSERT DATA { <http://example.org/keep> <http://example.org/keep> "x"@en'
);
ERROR:  invalid input syntax for type rdfnode: ""x"@en } ; INSERT DATA { <http://example.org/pwned> <http://example.org/pwned> <http://example.org/pwned> } ; INSERT DATA { <http://example.org/keep> <http://example.org/keep> "x"@en"
LINE 4:   '"x"@en } ; INSERT DATA { <http://example.org/pwned> <http...
          ^
SELECT count(*) FROM ft WHERE subject = '<http://example.org/pwned>';
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s 
{?s ?p ?o
 ## rdf_fdw pushdown conditions ##
 FILTER(?s = <http://example.org/pwned>)
}

INFO:  SPARQL returned 0 records.

 count 
-------
     0
(1 row)

-- value is the RDF literal whose lexical form is one backslash followed by
-- whatever the attacker wants the SPARQL engine to parse next.
INSERT INTO ft VALUES (
  '<http://example.org/s>',
  '<http://example.org/p>',
  E'"\\\\\\\\"'        -- the four-char string:  "  \  \  "
);
INFO:  SPARQL query sent to 'fuseki':
INSERT DATA { <http://example.org/s> <http://example.org/p> "\"\\\\"" };


ERROR:  bad request on server "fuseki" (HTTP 400)
DETAIL:  Lexical error at line 2, column 0.  Encountered: <EOF> after prefix "\" };\n"

HINT:  Check the SPARQL query syntax.
SELECT object FROM ft WHERE subject = '<http://example.org/s>';
INFO:  SPARQL query sent to 'fuseki':

SELECT ?s ?o 
{?s ?p ?o
 ## rdf_fdw pushdown conditions ##
 FILTER(?s = <http://example.org/s>)
}

INFO:  SPARQL returned 0 records.

 object 
--------
(0 rows)

/* Cleanup */
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