Producing NQuad dumps of Virtuoso Quad-store hosted RDF model data What? How to export RDF model data from Virtuoso's Quad Store in NQuad format. Why? When exporting RDF model data from Virtuoso's Quad Store, having the ability to retain and reflect Named Graph IRI based data partitioning provides significant value to a variety of application profiles. How? We have created stored procedures for the task. The dump procedure dump_nquads leverages SPARQL to facilitate data dump(s) for all graphs excluding the internal predefined "virtrdf:". Procedure Parameters The procedure dump_nquads has the following parameters: IN dir VARCHAR -- folder where the dumps will be stored. Note: The dump directory must be included in the DirsAllowed parameter of the Virtuoso configuration file (e.g., virtuoso.ini), or the Virtuoso server will not be able to create or access the data files. IN outstart_fromfile INTEGER -- output start from number n IN file_length_limit INTEGER -- maximum length of dump files IN comp INTEGER -- when set to 0, then no gzip will be done. By default is set to 1. Procedure Source The procedure dump_nquads has the following source: CREATE PROCEDURE dump_nquads ( IN dir VARCHAR := 'dumps' , IN start_from INT := 1 , IN file_length_limit INTEGER := 100000000 , IN comp INT := 1 ) { DECLARE inx, ses_len INT ; DECLARE file_name VARCHAR ; DECLARE env, ses ANY ; inx := start_from; SET isolation = 'uncommitted'; env := vector (0,0,0); ses := string_output (10000000); FOR (SELECT * FROM (sparql define input:storage "" SELECT ?s ?p ?o ?g { GRAPH ?g { ?s ?p ?o } . FILTER ( ?g != virtrdf: ) } ) AS sub OPTION (loop)) DO { DECLARE EXIT HANDLER FOR SQLSTATE '22023' { GOTO next; }; http_nquad (env, "s", "p", "o", "g", ses); ses_len := LENGTH (ses); IF (ses_len >= file_length_limit) { file_name := sprintf ('%s/output%06d.nq', dir, inx); string_to_file (file_name, ses, -2); IF (comp) { gz_compress_file (file_name, file_name||'.gz'); file_delete (file_name); } inx := inx + 1; env := vector (0,0,0); ses := string_output (10000000); } next:; } IF (length (ses)) { file_name := sprintf ('%s/output%06d.nq', dir, inx); string_to_file (file_name, ses, -2); IF (comp) { gz_compress_file (file_name, file_name||'.gz'); file_delete (file_name); } inx := inx + 1; env := vector (0,0,0); } } ; Example This example demonstrates calling the dump_nquads procedure to dump all graphs to a series of compressed NQuad dumps, each with uncompressed length of 10Mb (./dumps/output000001.nq.gz): SQL> dump_nquads ('dumps', 1, 10000000, 1); Related Virtuoso Tips and Tricks Collection RDF dumps from Virtuoso Quad store hosted data Virtuoso RDF Bulk Loader Virtuoso Documentation