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n2:VirtTipsAndTricksGuideQuadStorageInternally

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VirtTipsAndTricksGuideQuadStorageInternally

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VirtTipsAndTricksGuideQuadStorageInternally

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%META:TOPICPARENT{name="VirtTipsAndTricksGuide"}% ---++How can I see which quad storages exist and in which quad storage a graph resides? Let's take for example a [[http://virtuoso.openlinksw.com/whitepapers/relational%20rdf%20views%20mapping.html][created RDF view from relational data in Virtuoso]]. The RDF output therefor should have two graphs which reside in a quad storage named for ex.: <verbatim> http://localhost:8890/rdfv_demo/quad_storage/default </verbatim> Also the RDF is accessible over the SPARQL endpoint with the following query: <verbatim> define input:storage <http://localhost:8890/rdfv_demo/quad_storage/default> SELECT * WHERE { ?s ?p ?o } </verbatim> Now one could ask is there a way to define internally (once) that the quad storage should be included in queries to the SPARQL endpoint? So that the user does not have to define the <b>input:storage</b> explicitly in each query, like this: <verbatim> http://localhost:8890/sparql?query=select * where { ?s ?p ?o }&default-graph-uri=NULL&named-graph-uri=NULL </verbatim> All metadata about all RDF storages are kept in "system" graph &lt;http://www.openlinksw.com/schemas/virtrdf#&gt; ( namespace prefix <b>virtrdf:</b> ). Subjects of type <b>virtrdf:QuadStorage</b> are RDF storages. There are three of them by default: <verbatim> SQL> SPARQL SELECT * FROM virtrdf: WHERE { ?s a virtrdf:QuadStorage }; s VARCHAR _______________________________________________________________________________ http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage http://www.openlinksw.com/schemas/virtrdf#DefaultServiceStorage http://www.openlinksw.com/schemas/virtrdf#SyncToQuads 3 Rows. -- 3 msec. </verbatim> 1 <b>virtrdf:DefaultQuadStorage</b> is what's in use if no input:storage specified. 1 <b>virtrdf:DefaultServiceStorage</b> will be used for SPARQL federation. 1 <b>virtrdf:SyncToQuads</b> is to keep the list of Linked Data Views that are translated into RDB2RDF triggers. There are two ways of using the Linked Data View from above in SPARQL endpoint without <b>define input:storage</b>: 1. Create Linked Data View right in <b>virtrdf:DefaultQuadStorage</b> or add the view in other storage and then copy it from there to <b>virtrdf:DefaultQuadStorage</b>. * In any of these two variants, use: <verbatim> SPARQL ALTER QUAD STORAGE virtrdf:DefaultQuadStorage . . . </verbatim> 1. Use <b><nowiki>SYS_SPARQL_HOST</b></nowiki> table as described [[http://docs.openlinksw.com/virtuoso/rdfsparql.html#rdfdefaultgraph][here]] and set <b><nowiki>SH_DEFINES</b></nowiki> so it contains your favorite define input:storage ---+++Related * [[VirtTipsAndTricksGuide][Virtuoso Tips and Tricks Collection]] * [[http://docs.openlinksw.com/virtuoso/rdfsparql.html][SPARQL]]

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VirtTipsAndTricksGuideQuadStorageInternally

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2017-06-13T05:36:47Z

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