Virtuoso Tips and Tricks

We have a number of tips and tricks articles, covering various areas of Virtuoso functionality.

Database Administration

• How can I specify an OS user name to which the Virtuoso server will switch after opening the listen ports?
• How can I find out which tables are deadlocking?
• How can I configure parameters to avoid out of memory errors?
• How can I control normalization of UNICODE3 accented chars in the free-text index?
• What should I do if the Virtuoso Server is not responding to HTTP requests?
• How can I perform a checkpoint against a clustered Virtuoso Server?
• How can I handle checkpoint condition?
• How can I backup and restore individual table(s) and individual index(s) on a a new fresh db?
• How Do I Generate Transient and/or Persistent Linked Data Views atop ODBC or JDBC accessible Relational Data Sources?
• How Can I perform SQL login with X 509 WebID watermarked certificate?
• How do I recover from "Invalid log entry in replay" when transaction log is being replayed during server start?
• How can I move a Virtuoso database from one hardware and/or software platform to another?
• What should I do if the Virtuoso Server is not responding to HTTP requests?
• How can I set up Virtuoso Lite Mode?
• How can I use the LD Meter Utility?
• How to proxy Virtuoso HTTP server through Apache HTTP server front end?
• How to configure Virtuoso Cluster slave nodes HTTP listeners?
• How to configure Virtuoso Elastic Cluster?
• How to Monitor Virtuoso Memory Consumption?
• Linux libaio Library not found

RDF data management

• How can I obtain a list of all graphs?
• How to manage Graph Security Level for SQL Clients?
• How can I test whether two graphs are equal?
• How can I add triples to a graph?
• How can I update triples in a graph?
• How can I delete triples from a graph?
• How can I delete triples from a "Large" graph?
• How Can I Delete Triples containing blank nodes?
• How can I copy triples from one graph to another?
• How can I move triples from one graph to another?
• How can I drop a graph?
• What is the difference between "DELETE FROM GRAPH" and "CLEAR GRAPH"?
• How can I drop a graph for which is not clear was it created explicitly or not?
• How can I perform RDF dumps from Virtuoso Quad store hosted data?
• How can I perform Dump of RDF Graphs into NQuad dumps?
• How can I delete graphs using stored procedure?
• How Can I Delete Triple Patterns that are not scoped to a named graph?
• What are the differences between create, drop, clear and delete Graph?
• What are "Generate RDB2RDF triggers" and "Enable Data Syncs with Physical Quad Store" Linked Data Views options?
• How Can I Diagnose problems associated with Linked Data views generation?
• How can I display only some information from RDF graph?
• Can I drop and re-create the DefaultQuadStorage?
• How can I define a graph with virt:rdf_sponger option set to "on"?
• How can I configure Sponger to use Asynchronous Query (AQ) threads?
• How Do I Perform Bulk Loading of RDF Source Files into one or more Graph IRIs?
• How to exploit RDF Schema and OWL Inference Rules with minimal effort?
• How the power of OWL based inference enables us exploit the power of Linked Vocabularies?
• How can I insert binary data to Virtuoso RDF storage in plain queries and with parameter binding via ADO.NET calls?
• How can I replicate all graphs?
• How can I insert RDF data from Visual Studio to Virtuoso?
• How to rename a RDF Graph in the Virtuoso Quad Store?
• How can I configure Virtuoso for maximum performance with available memory?
• How can I use the LOAD command to import RDF data?
• How can I incorporate Content Negotiation into RDF bulk loaders?
• What free-text options can I use with bif:contains?
• How can use bif:contains after SPARUL INSERT?
• How Do I Gecode Data?
• How I Delete a Specific Triple Across Graphs?
• How Do I configure Sponger Cartridges?
• How Do I protect Sponger Endpoint via ACL-s?
• How do I administer Virtuoso Sponger Instance?
• How to control user agent usage of Sponger Resources?
• How Do I use transitive SPARQL query options and Exploit Inference Rules?
• How Do I use Transitivity via Inference Rules and Transitivity for lists?
• How Can I Import Linked Data using the Briefcase "Create" feature?
• What is the ShortenLongURIs Virtuoso configuration parameter?
• How can I fix RDF Quad Store Index corruption in commercial Release 6.2 and earlier builds
• How Can I perform Simple Linked Data Deployment using Virtuoso's HTTP Re-write Rules?
• How Can I Use Virtuoso's Anytime Query Feature?
• How Can I Split 3.4billion triple UniProt datasets file?
• How Can I insert triples via Digest Authentication into the Quad Store?
• How to Update Large SPARQL Data avoiding database checkpoint abortion?
• How can I Load Data into Virtuoso in Transaction Mode (ie auto commit OFF)?
• How to convert from Row Store to Column Store Table?
• How can I determine the time taken to load datasets with RDF Bulk Loader
• How to create a RDF Graph Replication slave Subscriber node from a master Publisher node

SPARQL and SPARUL (SPARQL/Update)

• What Virtuoso Sponger SPARQL pragmas are supported?
• Are Custom SPARQL Extension Functions supported and how can I use them?
• How do I configure Virtuoso to support "wide characters" (e.g., Unicode, UTF-8) for SPARQL querying?
• How can I optimize SPARQL query performance using bifs (built-in functions)?
• How can I generate a unique ID via SPARQL?
• What reification alternatives can I use for Linked Data publishing?
• Virtuoso Linked Data Deployment In 3 Simple Steps
• Is there a difference between a "merge" vs "one by one" execution of queries across named graphs?
• How can I use iSQL to execute SPARQL queries containing the dollar-sign ("$") character?
• How can I set the quad storage to be included in results of queries made to the SPARQL endpoint?
• How can I convert between data types using SPARQL in Virtuoso?
• Is it possible to have the SPARQL endpoint on a different port than the Conductor?
• How can I manage Date Range SPARQL queries?
• How to optimize bif:dateadd in SPARQL query using selective index-friendly filter?
• How do I use SPARUL to change a selection of property values from URI References to Literals?
• How can I use CONSTRUCT with Prepared Statements?
• How can I use Expressions inside CONSTRUCT, INSERT and DELETE?
• How can I use INSERT via CONSTRUCT Statements?
• How can perform SPARUL Updates without transactional log size getting exceed?
• How can I get certificate attributes using SPARQL?
• How does default DESCRIBE mode work?
• How can I dump arbitrary query result as N-Triples?
• How do I bind a named graph parameter in a prepared statement?
• How can I perform Case Insensitive Search across multiple literal values with Virtuoso?
• What is best method to get a random sample of all triples for a subset of all the resources of a SPARQL endpoint?
• How can I use SPARQL to make Meshups?
• How can I get an exact mapping for a date?
• How can I use SPARUL to add missing triples to a Named Graph
• How can I use the SPARQL IF operator for SPARQL-BI endpoint?
• How can I perform search for predicate values?
• How to clear graphs which are related to empty graphs?
• How can I enable Dynamic Extended Types (DETs) on a Virtuoso SPARQL Endpoint?
• How can I use sub-queries to enable literal values based joins?
• How can I execute query with labels preference order?
• How can I get object datatype?
• How to achieve best performance executing a query against SPARQL Endpoint?
• What methods can I use to protect SPARQL Endpoint?
• How Do I assign SPARQL role to SQL user?
• When should I use the function SAMPLE and when GROUP_CONCAT or GROUP_DIGEST?
• How can I include aggregate function values as objects in SPARQL CONSTRUCT queries?
• How Do I Clean Up Errant Data using SPARQL Update Language?
• How to Use SPARQL to add missing isDefinedBy relations to an Ontology?
• How to Import Ontology?
• How Can I Use MODIFY to update triples?
• What are the supported authentication methods associated with a purpose specific default SPARQL endpoint?
• How Can I execute INSERT/DELETE (SPARUL) statements against a WebID protected SPARQL endpoint?
• How to expose Linked Data View URIs associated with "References" on a given Table?
• How Can I perform SPARQL Date Arithmetic calculations?
• How Can I send SOAP requests to Virtuoso SPARQL Endpoint?
• How Can I manage Custom Controlling Virtuoso Labels for URI functionality?
• How Can I Prevent Limits of Sorted LIMIT/OFFSET query?
• How can I get a full "explain" and "profile" plans for a simple SPARQL query?
• How Can I Use the core feature of SPARQL logic of pattern matching?
• How To Let the SPARQL Endpoint Save Results In WebDAV?
• Where can I find examples for SPARQL 1.1 Features supported in Virtuoso?
  • How Can I use Built-In Functions?
  • How Can I use BIND?
  • How Can I use VALUES?
  • How Can I use Sub-queries?
  • How Can I use NOT EXISTS and MINUS?
  • How Can I use Assignments?
  • How Can I use Property Paths?
  • How Can I use SPARQL Named Graphs with SPARQL 1.1 Property Paths and Reasoning?
  • SPARQL 1.1 Update -- Graph Update:
    • How Can I use INSERT DATA?
    • How Can I use DELETE DATA?
    • How Can I use INSERT/DELETE DATA?
    • How Can I use LOAD?
    • How Can I use CLEAR?
    • How Can I use SPARQL 1.1 INSERT patterns and CONSTRUCT to Enhance Existing Data?
  • SPARQL 1.1 Update -- Graph Management:
    • How Can I use CREATE?
    • How Can I use DROP?
    • How Can I use COPY?
    • How Can I use MOVE?
  • SPARQL 1.1 Graph Store HTTP Protocol:
    • How Can I use HTTP POST, HTTP PUT, HTTP GET and HTTP DELETE?
• What SPARQL/SPARUL/SPARQL-BI Operations can I perform within Single/Multiple Statements?
• How Can I use the Virtuoso SPARQL LOAD Service?
• Where can I find examples for SPARQL Arithmetic Functions supported in Virtuoso?
• Where can I find examples for Linked Data SPARQL Reference Using the Gene Ontology?
• How Can I Escape double quotes in entity name?
• How can I use {is property of} syntax to express inverse relations in Turtle?
• How can I use the Virtuoso specific query optimizer hint ASSUME?
• How to discover the capabilities of a SPARQL endpoint en route to enhancing SPARQL-FED usage from Virtuoso instances using LOAD SERVICE ... DATA?
• How to add SPARQL Endpoint Capabilities Interrogation to Virtuoso SPARQL-FED functionality?
• How to discover parameters used by SPARQL services that don't support SPARQL-FED?
• How to handle SPARQL-FED queries for SPARQL endpoints with no OPTION() clause supported?
• How to split a urlencoded ";-" separated list of urls in a SPARQL query
• How Can I analyze Linked Open Data with R?
• How to interrogate attributes of a Virtuoso Server instance via SPARQL
• How can I run an aggregate like COUNT over multiple columns in SPARQL 1.1?

Pivot Viewer and CXML

• What are Pivot Collections and does Virtuoso support SPARQL CXML?
• What are the main components of the PivotViewer UI and Collection XML?
• Does the Virtuoso SPARQL protocol endpoint /sparql supports extensions to the SPARQL standard specifically for CXML?
• What RDF to CXML Mapping does Virtuoso support?
• What are the default settings for the CXML generation?
• Where can I find more details about the Auto-Detection of Facet Type?
• Configure the Query Timeout setting for the Virtuoso Facet Browser?
• What are the SparqlCxml Reserved Query Variables?
• How can I use the virtcxml graph?
• How can I use Labels in Place of URIs?
• What are the Link Typing specifics?
• Where can I find examples for SPARQL CXML Queries?
• What are the SparqlCxml Deep Zoom Collections for and how can I use them?
• How can I use the PivotViewer?
• How can I import CXML?
• What is the Facet Pivot Bridge?
• What are DETs and how can I used them for persisting SPARQL Query Results to DAV?
• What CXML params are supported for the SPARQL URL pattern?
• How can I change the Facet "Demo Queries" link?
• How can I change the Facet "/describe" page?

Other areas

• Who Am I
• How to attach a CSV document to Virtuoso Database Server Instance?
• How to read Virtuoso Transaction logs?
• How can I perform Query Optimization Diagnostics?
• Manage Linked (Open) Data
• How Can I Use OpenID+WebID?
• How can I use the WebID Identity Provider Proxy Service?
• How can I use the WebID Identity Verification Service?
• How can I use LDAP based WebIDs?
• How can I use the Virtuoso Mail Verification Service?
• How can I enable the Virtuoso Entity Framework 3.5 ADO.Net Provider in Visual Studio 2010?
• How can I write custom crawler using PL?
• How can I make Multi Thread Virtuoso connection using JDBC?
• How can I output the result of a SQL SELECT query from isql to a file in Virtuoso?
• How can I output the results of a SPARQL query run against the /sparql endpoint to a file in Virtuoso?
• How can I setup Server-side Cross-Origin Resource Sharing (CORS) using Virtuoso?
• How can I perform Cross-Origin Resource Sharing (CORS) to enable a Virtuoso SPARQL Endpoint?
• How Can I execute load of sql dump from jdbc?
• How can I make Recording in Virtuoso?
• How can I make internal HTTP redirects?
• Virtuoso Data Center Tips and Tricks
• Understanding Relationship semantics and reasoning
• How to Determine Data Usage?
• How to configure the User Agent Identity used by a Virtuoso Sponger instance?
• How to Manage SSL Protocols and Ciphers used with Virtuoso?
• How to extend URIQA DefaultHost value for properly using Facet Browser as search engine?
• Understanding Virtuoso Timezoneless Datetimes