o Scripts to Dump and Reload RDF Graphs
Every DBMS needs to offer a mechanism for bulk export and import of data.
Virtuoso supports dumping and reloading graph model data (e.g., RDF), as well as relational data (e.g., SQL) (discussed elsewhere).
We have created stored procedures for the task. The dump procedures leverage SPARQL to facilitate selective data dump(s) from one or more Named Graphs, each denoted by an IRI.
IN srcgraph VARCHAR
-- IN out_file VARCHAR
-- IN file_length_limit INTEGER
-- maximum length of dump filesCREATE PROCEDURE dump_one_graph ( IN srcgraph VARCHAR , IN out_file VARCHAR , IN file_length_limit INTEGER := 1000000000 ) { DECLARE file_name varchar; DECLARE env, ses any; DECLARE ses_len, max_ses_len, file_len, file_idx integer; SET ISOLATION = 'uncommitted'; max_ses_len := 10000000; file_len := 0; file_idx := 1; file_name := sprintf ('%s%06d.ttl', out_file, file_idx); string_to_file ( file_name || '.graph', srcgraph, -2 ); string_to_file ( file_name, sprintf ( '# Dump of graph <%s>, as of %s\n', srcgraph, CAST (NOW() AS VARCHAR) ), -2 ); env := vector (dict_new (16000), 0, '', '', '', 0, 0, 0, 0); ses := string_output (); FOR (SELECT * FROM ( SPARQL DEFINE input:storage "" SELECT ?s ?p ?o { GRAPH `iri(?:srcgraph)` { ?s ?p ?o } } ) AS sub OPTION (LOOP)) DO { http_ttl_triple (env, "s", "p", "o", ses); ses_len := length (ses); IF (ses_len > max_ses_len) { file_len := file_len + ses_len; IF (file_len > file_length_limit) { http (' .\n', ses); string_to_file (file_name, ses, -1); file_len := 0; file_idx := file_idx + 1; file_name := sprintf ('%s%06d.ttl', out_file, file_idx); string_to_file ( file_name, sprintf ( '# Dump of graph <%s>, as of %s (part %d)\n', srcgraph, CAST (NOW() AS VARCHAR), file_idx), -2 ); env := vector (dict_new (16000), 0, '', '', '', 0, 0, 0, 0); } ELSE string_to_file (file_name, ses, -1); ses := string_output (); } } IF (LENGTH (ses)) { http (' .\n', ses); string_to_file (file_name, ses, -1); } } ;
The dump_graphs
procedure can be used to dump all the graphs in a Virtuoso server to a set of turtle (.ttl
) data files in the specified dump directory.
IN dir VARCHAR
-- dump directory IN file_length_limit INTEGER
-- maximum length of dump filesDirsAllowed?
parameter of the Virtuoso configuration file (virtuoso.ini
), or the Virtuoso server will not be able to create or access the data files.CREATE PROCEDURE dump_graphs ( IN dir VARCHAR := 'dumps' , IN file_length_limit INTEGER := 1000000000 ) { DECLARE inx INT; inx := 1; SET ISOLATION = 'uncommitted'; FOR ( SELECT * FROM ( SPARQL DEFINE input:storage "" SELECT DISTINCT ?g { GRAPH ?g { ?s ?p ?o } . FILTER ( ?g != virtrdf: ) } ) AS sub OPTION ( LOOP )) DO { dump_one_graph ( "g", sprintf ('%s/graph%06d_', dir, inx), file_length_limit ); inx := inx + 1; } } ;
The load_graphs
procedure can then be used to load a dumped dataset's ttl
files into a Virtuoso Server instance.
IN dir VARCHAR
- dump directoryDirsAllowed?
parameter of the Virtuoso configuration file (virtuoso.ini
), or the Virtuoso server will not be able to access the data file(s).CREATE PROCEDURE load_graphs ( IN dir VARCHAR := 'dumps/' ) { DECLARE arr ANY; DECLARE g VARCHAR; arr := sys_dirlist (dir, 1); log_enable (2, 1); FOREACH (VARCHAR f IN arr) DO { IF (f LIKE '*.ttl') { DECLARE CONTINUE HANDLER FOR SQLSTATE '*' { log_message (sprintf ('Error in %s', f)); }; g := file_to_string (dir || '/' || f || '.graph'); DB.DBA.TTLP_MT (file_open (dir || '/' || f), g, g, 255); } } EXEC ('CHECKPOINT'); } ;
dump_one_graph
procedure with appropriate arguments:
$ pwd /Applications/OpenLink Virtuoso/Virtuoso 6.1/database $ grep DirsAllowed virtuoso.ini DirsAllowed = ., ../vad, ./dumps $ /opt/virtuoso/bin/isql 1111 Connected to OpenLink Virtuoso Driver: 06.01.3127 OpenLink Virtuoso ODBC Driver OpenLink Interactive SQL (Virtuoso), version 0.9849b. Type HELP; for help and EXIT; to exit.SQL> dump_one_graph ('http://daas.openlinksw.com/data#', './data_', 1000000000); Done. -- 1438 msec.
data_XX
(located in your Virtuoso db folder):
<verbatim> $ ls dumps data_000001.ttl data_000002.ttl .... data_000001.ttl.graph
dump_graphs
procedure:
$ pwd /Applications/OpenLink Virtuoso/Virtuoso 6.1/database $ grep DirsAllowed virtuoso.ini DirsAllowed = ., ../vad, ./dumps $ /opt/virtuoso/bin/isql 1111 Connected to OpenLink Virtuoso Driver: 06.01.3127 OpenLink Virtuoso ODBC Driver OpenLink Interactive SQL (Virtuoso), version 0.9849b. Type HELP; for help and EXIT; to exit. SQL> dump_graphs(); Done. -- 998 msec. SQL> quit;
dumps/data_XX
(located in your Virtuoso db folder):
$ ls dumps graph000001_000001.ttl graph000005_000001.ttl graph000001_000001.ttl.graph graph000005_000001.ttl.graph graph000002_000001.ttl graph000006_000001.ttl graph000002_000001.ttl.graph graph000006_000001.ttl.graph graph000003_000001.ttl graph000007_000001.ttl graph000003_000001.ttl.graph graph000007_000001.ttl.graph graph000004_000001.ttl graph000008_000001.ttl graph000004_000001.ttl.graph graph000008_000001.ttl.graph
$ /opt/virtuoso/bin/isql 1112 Connected to OpenLink Virtuoso Driver: 06.01.3127 OpenLink Virtuoso ODBC Driver OpenLink Interactive SQL (Virtuoso), version 0.9849b. Type HELP; for help and EXIT; to exit. SQL> load_graphs(); Done. -- 2392 msec. SQL>