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2018-04-13T12:08:30.296415

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2019-05-13T11:15:48.438009

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VirtTipsAndTricksAnalyzingSPARQLQuery

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VirtTipsAndTricksAnalyzingSPARQLQuery

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%META:TOPICPARENT{name="VirtTipsAndTricksGuide"}% ---+ How can I get full <code>explain</code> and <code>profile</code> plans for a simple SPARQL query? Starting with Virtuoso Commercial Release 6.4, and Virtuoso Open Source 6.1.5, <code>isql</code> offers 2 new modes for analyzing SPARQL queries: 1 Translate a SPARQL query into the correspondent SQL: <verbatim> SQL> SET SPARQL_TRANSLATE ON; SQL> SELECT * FROM <graph> WHERE {?S a ?O}; ---> Or execute query of your choice SQL> SET SPARQL_TRANSLATE OFF; </verbatim> 1 Generate compilation plan of an SQL query: <verbatim> SQL> SET EXPLAIN ON; SQL> SELECT * FROM TABLE WHERE field = 'text'; ---> Or execute query of your choice SQL> SET EXPLAIN OFF; </verbatim> * The equivalent is <code>[[http://docs.openlinksw.com/virtuoso/fn_explain/][EXPLAIN()]]</code>, which is much more difficult to use; you cannot just copy-and-paste a query, as all quotes must be doubled within the <code>EXPLAIN(' ... ')</code>, as shown below: <verbatim> SQL> explain('select * from table where field = ''text'''); </verbatim> 1 Generate compilation and execution plan of an SQL query: <verbatim> SQL> SET PROFILE ON; SQL> SELECT * FROM TABLE WHERE field = 'text'; ---> Or execute query of your choice SQL> SET PROFILE OFF; </verbatim> * The equivalent (available in Virtuoso 7 and later) is <code>[[http://docs.openlinksw.com/virtuoso/fn_profile/][PROFILE()]]</code>, which is much more difficult to use; you cannot just copy-and-paste a query, as all quotes must be doubled within the <code>PROFILE(' ... ')</code>, as shown below: <verbatim> SQL> profile('select * from table where field = ''text'''); </verbatim> 1 A more detailed query profile (compilation and execution) with cardinality can be obtained by executing the following following sequence <verbatim> SQL> __dbf_set('enable_qr_comment', 1); SQL> __dbf_set('dbf_explain_level', 3); SQL> SET PROFILE ON; SQL> SET BLOBS ON; SQL> SELECT * FROM TABLE WHERE field = 'text'; ---> Or execute query of your choice SQL> SET PROFILE OFF; </verbatim> Provide the generated plans for analysis. ---++ Example Here is a simple example of how to combine the two options to get a full <code>explain()</code> plan for a simple SPARQL query: 1 Assume the following query: <verbatim> SELECT * FROM <http://dbpedia.org> WHERE { ?s a ?o } LIMIT 10 </verbatim> 1. Use the <code>isql</code> command line tool to connect to your database, and execute: <verbatim> SQL> SET BLOBS ON; -- in case output is very large SQL> SET SPARQL_TRANSLATE ON; SQL> SELECT * FROM <http://dbpedia.org> WHERE {?s a ?o} LIMIT 10; SPARQL_TO_SQL_TEXT VARCHAR _______________________________________________________________________________ SELECT TOP 10 __id2i ( "s_1_0-t0"."S" ) AS "s", __ro2sq ( "s_1_0-t0"."O" ) AS "o" FROM DB.DBA.RDF_QUAD AS "s_1_0-t0" WHERE "s_1_0-t0"."G" = __i2idn ( __bft( 'http://dbpedia.org' , 1)) AND "s_1_0-t0"."P" = __i2idn ( __bft( 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type' , 1)) OPTION (QUIETCAST) 1 Rows. -- 1 msec. SQL> SET SPARQL_TRANSLATE OFF; </verbatim> 1. Use your mouse to select the query output, and paste it after the <code>SET EXPLAIN ON;</code> command. Then hit the ENTER key. <verbatim> SQL> SET EXPLAIN ON; SQL> SELECT TOP 10 __id2i ( "s_1_0-t0"."S" ) AS "s", __ro2sq ( "s_1_0-t0"."O" ) AS "o" FROM DB.DBA.RDF_QUAD AS "s_1_0-t0" WHERE "s_1_0-t0"."G" = __i2idn ( __bft( 'http://dbpedia.org' , 1)) AND "s_1_0-t0"."P" = __i2idn ( __bft( 'http://www.w3.org/1999/02/22-rdf-syn tax-ns#type' , 1)) OPTION (QUIETCAST) ; REPORT VARCHAR _______________________________________________________________________________ { from DB.DBA.RDF_QUAD by RDF_QUAD_POGS 4.5e+05 rows Key RDF_QUAD_POGS ASC ($22 "s_1_0-t0.S", $21 "s_1_0-t0.O") inlined <col=556 P = #type > row specs: <col=554 G = #http://dbpedia.org > After code: 0: $25 "s" := Call __id2i ($22 "s_1_0-t0.S") 5: $26 "o" := Call __ro2sq ($21 "s_1_0-t0.O") 10: BReturn 0 Select (TOP 10 ) ($25 "s", $26 "o", <$24 "<DB.DBA.RDF_QUAD s_1_0-t0>" spec 5>) } 13 Rows. -- 1 msec. SQL> SET EXPLAIN OFF; </verbatim> ---++Related * [[VirtTipsAndTricksGuide][Virtuoso Tips and Tricks Collection]] * [[http://docs.openlinksw.com/virtuoso/rdfsparql.html][Virtuoso Documentation]]

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2018-04-13T12:08:30Z

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2019-05-13T11:15:48Z

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