Frequently Asked Questions

Virtuoso Universal Server

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ABAC
Are there any Virtuoso plans for Cloud technologies (Openstack, etc.)?
Virtuoso Open Source Edition (VOS) is part of the LOD2 OpenStack deliverables, but this does not include Enterprise Edition features (i.e., no replication clustering, elastic clustering, fine-grained ABAC security, nor virtual DBMS functionality for making RDF views over external SQL data sources). That said, Virtuoso (both Open Source and Enterprise) may be instatiated on cloud services, including Amazon EC2.
Conceptual Data Virtualization
How do I create RDF-based Linked Data Views over Relational Data Sources?
This page discusses the basics of creating RDF-based Linked Data Views over Relational Data Sourcesand links to several other pages with specific guides for various local and remote (ODBC- and JDBC-accessible) data sources.
Conceptual Data Virtualization
How do I use R2RML to map RDB to RDF with Virtuoso?
R2RML, a W3C Recommendation, is a language for expressing customized mappings from relational databases to RDF data sets. Such mappings provide the ability to view existing relational data in the RDF data model, expressed in a structure and target vocabulary of the mapping author's choice. R2RML mappings are themselves RDF graphs written in Turtle syntax. R2RML is becoming the generic standard adopted by most vendors of tools mapping relational data to RDF, enabling the interoperability of R2RML scripts, whether created with such tools or by hand. This page discusses how to use R2RML specifically with Virtuoso.
Conceptual Data Virtualization
How do I use just one click on Virtuoso's HTML-based Wizard to Generate and Deploy RDF-based Linked Data from Relational Databases?
See example of One-Click Linked Data Generation & Deployment of Linked Data Views over Relational Data Sources with Virtuoso.
Data Virtualization
How do I attach the Virtuoso Virtual Database Engine to ODBC- or JDBC-accessible Data Sources?
See OpenLink How-To guides to learn how to connect Virtuoso's Virtual Database Engine to local or remote data sources including Firebird, DB2, Informix, Ingres, MySQL, Microsoft SQL Server, Oracle, PostgreSQL, Progress, Sybaseand others accessible by ODBC or JDBC. (Note - JDBC requires an ODBC-to-JDBC Bridge, which OpenLink may also supply.)
Data Virtualization
How do I create RDF-based Linked Data Views over Relational Data Sources?
This page discusses the basics of creating RDF-based Linked Data Views over Relational Data Sourcesand links to several other pages with specific guides for various local and remote (ODBC- and JDBC-accessible) data sources.
Data Virtualization
How do I use R2RML to map RDB to RDF with Virtuoso?
R2RML, a W3C Recommendation, is a language for expressing customized mappings from relational databases to RDF data sets. Such mappings provide the ability to view existing relational data in the RDF data model, expressed in a structure and target vocabulary of the mapping author's choice. R2RML mappings are themselves RDF graphs written in Turtle syntax. R2RML is becoming the generic standard adopted by most vendors of tools mapping relational data to RDF, enabling the interoperability of R2RML scripts, whether created with such tools or by hand. This page discusses how to use R2RML specifically with Virtuoso.
Data Virtualization
How do I use just one click on Virtuoso's HTML-based Wizard to Generate and Deploy RDF-based Linked Data from Relational Databases?
See example of One-Click Linked Data Generation & Deployment of Linked Data Views over Relational Data Sources with Virtuoso.
Cluster Module
Do I have to stop the cluster to add a node or partition an index?
If the "elastic cluster" option is enabled at DB creation time, adding nodes and repartitioning indexes can be done without stopping the cluster.
Cluster Module
What are the best options to offer High-Avaliability and Disaster Recovery? Is it possible to move data from one datacenter to another and how is data transferred? Are there any numbers about the speed of data replication between two datacenters and consistency of the process?
You can use replication for HA across Elastic Clusters or Single-Server instances. For example, nearly-instantaneous Transactional Replication is used by some of our larger customers (e.g., Globo of Brazil used a Transactional Replication setup for the entire World Cup 2014 without any issues).
Cluster Module
What is the Virtuoso strategy to scale? Is it possible to start small and then add servers if needed?
Yes. You start with Single-Server, enable the Elastic Cluster optionand then add nodes as scalability demands increase.
Cluster Module
What is the differences in terms of performance/scalability between 2 cluster configurations?
Configuration A: 4 cluster nodes, 3 instances per cluster node (quorum), 1 instance per host cluster node, 12 host cluster nodes. Configuration B: 4 cluster nodes, 3 instances per cluster node (quorum), 4 instances per host cluster node, 3 host cluster nodes. Performance has more to do with the number of Virtuoso Server processes running on each cluster node. One instance per cluster node will work better than four instances per cluster node. You will have more OS resources available as the Virtuoso instances are reduced. Ideally, you want to spread the instances over distinct machines so that you have resources pooled across those machines.
Cluster Module
When will federation of triple stores be available in Virtuosoand how does it compare to clustering?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created. Clustering has more to do with horizontal partitioning of the database across many machines (physical or virtual) to parallelize execution of queries, etc. SPARQL-FED may be used with a Virtuoso Cluster, just as with a Single-Server Instance.
Virtuoso Cluster
Are there any Virtuoso plans for Cloud technologies (Openstack, etc.)?
Virtuoso Open Source Edition (VOS) is part of the LOD2 OpenStack deliverables, but this does not include Enterprise Edition features (i.e., no replication clustering, elastic clustering, fine-grained ABAC security, nor virtual DBMS functionality for making RDF views over external SQL data sources). That said, Virtuoso (both Open Source and Enterprise) may be instatiated on cloud services, including Amazon EC2.
Virtuoso Cluster
Do I have to stop the cluster to add a node or partition an index?
If the "elastic cluster" option is enabled at DB creation time, adding nodes and repartitioning indexes can be done without stopping the cluster.
Virtuoso Cluster
What are the best options to offer High-Avaliability and Disaster Recovery? Is it possible to move data from one datacenter to another and how is data transferred? Are there any numbers about the speed of data replication between two datacenters and consistency of the process?
You can use replication for HA across Elastic Clusters or Single-Server instances. For example, nearly-instantaneous Transactional Replication is used by some of our larger customers (e.g., Globo of Brazil used a Transactional Replication setup for the entire World Cup 2014 without any issues).
Virtuoso Cluster
What is the Virtuoso strategy to scale? Is it possible to start small and then add servers if needed?
Yes. You start with Single-Server, enable the Elastic Cluster optionand then add nodes as scalability demands increase.
Virtuoso Cluster
What is the differences in terms of performance/scalability between 2 cluster configurations?
Configuration A: 4 cluster nodes, 3 instances per cluster node (quorum), 1 instance per host cluster node, 12 host cluster nodes. Configuration B: 4 cluster nodes, 3 instances per cluster node (quorum), 4 instances per host cluster node, 3 host cluster nodes. Performance has more to do with the number of Virtuoso Server processes running on each cluster node. One instance per cluster node will work better than four instances per cluster node. You will have more OS resources available as the Virtuoso instances are reduced. Ideally, you want to spread the instances over distinct machines so that you have resources pooled across those machines.
Virtuoso Cluster
When will federation of triple stores be available in Virtuosoand how does it compare to clustering?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created. Clustering has more to do with horizontal partitioning of the database across many machines (physical or virtual) to parallelize execution of queries, etc. SPARQL-FED may be used with a Virtuoso Cluster, just as with a Single-Server Instance.
Virtuoso Cluster Node (VCN)
Do I have to stop the cluster to add a node or partition an index?
If the "elastic cluster" option is enabled at DB creation time, adding nodes and repartitioning indexes can be done without stopping the cluster.
Virtuoso Cluster Node (VCN)
What is the Virtuoso strategy to scale? Is it possible to start small and then add servers if needed?
Yes. You start with Single-Server, enable the Elastic Cluster optionand then add nodes as scalability demands increase.
Virtuoso Replication Cluster
Are there any Virtuoso plans for Cloud technologies (Openstack, etc.)?
Virtuoso Open Source Edition (VOS) is part of the LOD2 OpenStack deliverables, but this does not include Enterprise Edition features (i.e., no replication clustering, elastic clustering, fine-grained ABAC security, nor virtual DBMS functionality for making RDF views over external SQL data sources). That said, Virtuoso (both Open Source and Enterprise) may be instatiated on cloud services, including Amazon EC2.
Virtuoso Replication Cluster
What are the best options to offer High-Avaliability and Disaster Recovery? Is it possible to move data from one datacenter to another and how is data transferred? Are there any numbers about the speed of data replication between two datacenters and consistency of the process?
You can use replication for HA across Elastic Clusters or Single-Server instances. For example, nearly-instantaneous Transactional Replication is used by some of our larger customers (e.g., Globo of Brazil used a Transactional Replication setup for the entire World Cup 2014 without any issues).
Virtuoso Server Instance (VSI)
Are there any Virtuoso plans for Cloud technologies (Openstack, etc.)?
Virtuoso Open Source Edition (VOS) is part of the LOD2 OpenStack deliverables, but this does not include Enterprise Edition features (i.e., no replication clustering, elastic clustering, fine-grained ABAC security, nor virtual DBMS functionality for making RDF views over external SQL data sources). That said, Virtuoso (both Open Source and Enterprise) may be instatiated on cloud services, including Amazon EC2.
Virtuoso Server Instance (VSI)
Do I have to stop the cluster to add a node or partition an index?
If the "elastic cluster" option is enabled at DB creation time, adding nodes and repartitioning indexes can be done without stopping the cluster.
Virtuoso Server Instance (VSI)
What are the best options to offer High-Avaliability and Disaster Recovery? Is it possible to move data from one datacenter to another and how is data transferred? Are there any numbers about the speed of data replication between two datacenters and consistency of the process?
You can use replication for HA across Elastic Clusters or Single-Server instances. For example, nearly-instantaneous Transactional Replication is used by some of our larger customers (e.g., Globo of Brazil used a Transactional Replication setup for the entire World Cup 2014 without any issues).
Virtuoso Server Instance (VSI)
What is the Virtuoso strategy to scale? Is it possible to start small and then add servers if needed?
Yes. You start with Single-Server, enable the Elastic Cluster optionand then add nodes as scalability demands increase.
Virtuoso Server Instance (VSI)
When will federation of triple stores be available in Virtuosoand how does it compare to clustering?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created. Clustering has more to do with horizontal partitioning of the database across many machines (physical or virtual) to parallelize execution of queries, etc. SPARQL-FED may be used with a Virtuoso Cluster, just as with a Single-Server Instance.
Virtuoso Shared-Nothing Cluster
Are there any Virtuoso plans for Cloud technologies (Openstack, etc.)?
Virtuoso Open Source Edition (VOS) is part of the LOD2 OpenStack deliverables, but this does not include Enterprise Edition features (i.e., no replication clustering, elastic clustering, fine-grained ABAC security, nor virtual DBMS functionality for making RDF views over external SQL data sources). That said, Virtuoso (both Open Source and Enterprise) may be instatiated on cloud services, including Amazon EC2.
Virtuoso Shared-Nothing Cluster
Do I have to stop the cluster to add a node or partition an index?
If the "elastic cluster" option is enabled at DB creation time, adding nodes and repartitioning indexes can be done without stopping the cluster.
Virtuoso Shared-Nothing Cluster
What are the best options to offer High-Avaliability and Disaster Recovery? Is it possible to move data from one datacenter to another and how is data transferred? Are there any numbers about the speed of data replication between two datacenters and consistency of the process?
You can use replication for HA across Elastic Clusters or Single-Server instances. For example, nearly-instantaneous Transactional Replication is used by some of our larger customers (e.g., Globo of Brazil used a Transactional Replication setup for the entire World Cup 2014 without any issues).
Virtuoso Shared-Nothing Cluster
What is the Virtuoso strategy to scale? Is it possible to start small and then add servers if needed?
Yes. You start with Single-Server, enable the Elastic Cluster optionand then add nodes as scalability demands increase.
Virtuoso Shared-Nothing Cluster
What is the differences in terms of performance/scalability between 2 cluster configurations?
Configuration A: 4 cluster nodes, 3 instances per cluster node (quorum), 1 instance per host cluster node, 12 host cluster nodes. Configuration B: 4 cluster nodes, 3 instances per cluster node (quorum), 4 instances per host cluster node, 3 host cluster nodes. Performance has more to do with the number of Virtuoso Server processes running on each cluster node. One instance per cluster node will work better than four instances per cluster node. You will have more OS resources available as the Virtuoso instances are reduced. Ideally, you want to spread the instances over distinct machines so that you have resources pooled across those machines.
Virtuoso Shared-Nothing Cluster
When will federation of triple stores be available in Virtuosoand how does it compare to clustering?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created. Clustering has more to do with horizontal partitioning of the database across many machines (physical or virtual) to parallelize execution of queries, etc. SPARQL-FED may be used with a Virtuoso Cluster, just as with a Single-Server Instance.
Java Database Connectivity (JDBC)
How do I attach the Virtuoso Virtual Database Engine to ODBC- or JDBC-accessible Data Sources?
See OpenLink How-To guides to learn how to connect Virtuoso's Virtual Database Engine to local or remote data sources including Firebird, DB2, Informix, Ingres, MySQL, Microsoft SQL Server, Oracle, PostgreSQL, Progress, Sybaseand others accessible by ODBC or JDBC. (Note - JDBC requires an ODBC-to-JDBC Bridge, which OpenLink may also supply.)
Java Database Connectivity (JDBC)
How do I create RDF-based Linked Data Views over Relational Data Sources?
This page discusses the basics of creating RDF-based Linked Data Views over Relational Data Sourcesand links to several other pages with specific guides for various local and remote (ODBC- and JDBC-accessible) data sources.
Java Database Connectivity (JDBC)
How do I use R2RML to map RDB to RDF with Virtuoso?
R2RML, a W3C Recommendation, is a language for expressing customized mappings from relational databases to RDF data sets. Such mappings provide the ability to view existing relational data in the RDF data model, expressed in a structure and target vocabulary of the mapping author's choice. R2RML mappings are themselves RDF graphs written in Turtle syntax. R2RML is becoming the generic standard adopted by most vendors of tools mapping relational data to RDF, enabling the interoperability of R2RML scripts, whether created with such tools or by hand. This page discusses how to use R2RML specifically with Virtuoso.
Java Database Connectivity (JDBC)
How do I use just one click on Virtuoso's HTML-based Wizard to Generate and Deploy RDF-based Linked Data from Relational Databases?
See example of One-Click Linked Data Generation & Deployment of Linked Data Views over Relational Data Sources with Virtuoso.
Linked Data
How do I explore Linked Data using the HTML5-based Pivot Viewer?
See OpenLink How-To guide that showcases how to use a Virtuoso hosted instance of the Microsoft PivotViewer as a Linked Data front-end for follow-your-nose data exploration.
Linked Data
How do I explore Linked Data using the Microsoft Pivot Viewer?
See OpenLink How-To guide that showcases how to use a Virtuoso hosted instance of the Microsoft PivotViewer as a Linked Data front-end for follow-your-nose data exploration.
Linked Data
How do I install and configure the Virtuoso Faceted Browser?
See required prerequisites, pre-installation steps, VAD package installation, post-installation stepsand example tutorials.
Linked Data
How do I use Virtuoso to deploy Linked Data to the Web?
This page discusses some of the difficulties faced in exposing RDF data and in bridging the "Linked Data Web" and the traditional "Document Web". Two generic approaches to resolving these deployment challenges - content negotiation and URL rewriting - are described, before looking at OpenLink Virtuoso, from the standpoint of both how it implements these solutions and how Linked Data is deployed.
NewSQL
Is Virtuoso currently evaluating NoSQL database for the storage of quads?
Virtuoso is a Native Hybrid DBMS - it is SQL and NoSQL combined.
NoSQL
Is Virtuoso currently evaluating NoSQL database for the storage of quads?
Virtuoso is a Native Hybrid DBMS - it is SQL and NoSQL combined.
Open Database Connectivity (ODBC)
How do I attach the Virtuoso Virtual Database Engine to ODBC- or JDBC-accessible Data Sources?
See OpenLink How-To guides to learn how to connect Virtuoso's Virtual Database Engine to local or remote data sources including Firebird, DB2, Informix, Ingres, MySQL, Microsoft SQL Server, Oracle, PostgreSQL, Progress, Sybaseand others accessible by ODBC or JDBC. (Note - JDBC requires an ODBC-to-JDBC Bridge, which OpenLink may also supply.)
Open Database Connectivity (ODBC)
How do I create RDF-based Linked Data Views over Relational Data Sources?
This page discusses the basics of creating RDF-based Linked Data Views over Relational Data Sourcesand links to several other pages with specific guides for various local and remote (ODBC- and JDBC-accessible) data sources.
Open Database Connectivity (ODBC)
How do I use R2RML to map RDB to RDF with Virtuoso?
R2RML, a W3C Recommendation, is a language for expressing customized mappings from relational databases to RDF data sets. Such mappings provide the ability to view existing relational data in the RDF data model, expressed in a structure and target vocabulary of the mapping author's choice. R2RML mappings are themselves RDF graphs written in Turtle syntax. R2RML is becoming the generic standard adopted by most vendors of tools mapping relational data to RDF, enabling the interoperability of R2RML scripts, whether created with such tools or by hand. This page discusses how to use R2RML specifically with Virtuoso.
Open Database Connectivity (ODBC)
How do I use just one click on Virtuoso's HTML-based Wizard to Generate and Deploy RDF-based Linked Data from Relational Databases?
See example of One-Click Linked Data Generation & Deployment of Linked Data Views over Relational Data Sources with Virtuoso.
SQL Relational Tables to RDF Property (Predicate) Graph Mapping Language
How do I create RDF-based Linked Data Views over Relational Data Sources?
This page discusses the basics of creating RDF-based Linked Data Views over Relational Data Sourcesand links to several other pages with specific guides for various local and remote (ODBC- and JDBC-accessible) data sources.
SQL Relational Tables to RDF Property (Predicate) Graph Mapping Language
How do I use R2RML to map RDB to RDF with Virtuoso?
R2RML, a W3C Recommendation, is a language for expressing customized mappings from relational databases to RDF data sets. Such mappings provide the ability to view existing relational data in the RDF data model, expressed in a structure and target vocabulary of the mapping author's choice. R2RML mappings are themselves RDF graphs written in Turtle syntax. R2RML is becoming the generic standard adopted by most vendors of tools mapping relational data to RDF, enabling the interoperability of R2RML scripts, whether created with such tools or by hand. This page discusses how to use R2RML specifically with Virtuoso.
SQL Relational Tables to RDF Property (Predicate) Graph Mapping Language
How do I use just one click on Virtuoso's HTML-based Wizard to Generate and Deploy RDF-based Linked Data from Relational Databases?
See example of One-Click Linked Data Generation & Deployment of Linked Data Views over Relational Data Sources with Virtuoso.
SPARQL
What is the current status of development for Virtuoso federation of triple stores?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created.
SPARQL
When will federation of triple stores be available in Virtuosoand how does it compare to clustering?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created. Clustering has more to do with horizontal partitioning of the database across many machines (physical or virtual) to parallelize execution of queries, etc. SPARQL-FED may be used with a Virtuoso Cluster, just as with a Single-Server Instance.
Federated SPARQL
What is the current status of development for Virtuoso federation of triple stores?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created.
Federated SPARQL
When will federation of triple stores be available in Virtuosoand how does it compare to clustering?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created. Clustering has more to do with horizontal partitioning of the database across many machines (physical or virtual) to parallelize execution of queries, etc. SPARQL-FED may be used with a Virtuoso Cluster, just as with a Single-Server Instance.
SPARQL Query Language
How do I use SPARQL to dynamically generate CXML collections for the Microsoft or HTML5-based PivotViewer?
See OpenLink How-To guide that demonstrates the generation of CXML-based output from SPARQL queries. This output is then used as input for the Microsoft or HTML5-based PivotViewer.
SQL Relational Database Management System
Is Virtuoso currently evaluating NoSQL database for the storage of quads?
Virtuoso is a Native Hybrid DBMS - it is SQL and NoSQL combined.
Clustering
Are there any Virtuoso plans for Cloud technologies (Openstack, etc.)?
Virtuoso Open Source Edition (VOS) is part of the LOD2 OpenStack deliverables, but this does not include Enterprise Edition features (i.e., no replication clustering, elastic clustering, fine-grained ABAC security, nor virtual DBMS functionality for making RDF views over external SQL data sources). That said, Virtuoso (both Open Source and Enterprise) may be instatiated on cloud services, including Amazon EC2.
Clustering
Do I have to stop the cluster to add a node or partition an index?
If the "elastic cluster" option is enabled at DB creation time, adding nodes and repartitioning indexes can be done without stopping the cluster.
Clustering
What are the best options to offer High-Avaliability and Disaster Recovery? Is it possible to move data from one datacenter to another and how is data transferred? Are there any numbers about the speed of data replication between two datacenters and consistency of the process?
You can use replication for HA across Elastic Clusters or Single-Server instances. For example, nearly-instantaneous Transactional Replication is used by some of our larger customers (e.g., Globo of Brazil used a Transactional Replication setup for the entire World Cup 2014 without any issues).
Clustering
What is the Virtuoso strategy to scale? Is it possible to start small and then add servers if needed?
Yes. You start with Single-Server, enable the Elastic Cluster optionand then add nodes as scalability demands increase.
Clustering
What is the differences in terms of performance/scalability between 2 cluster configurations?
Configuration A: 4 cluster nodes, 3 instances per cluster node (quorum), 1 instance per host cluster node, 12 host cluster nodes. Configuration B: 4 cluster nodes, 3 instances per cluster node (quorum), 4 instances per host cluster node, 3 host cluster nodes. Performance has more to do with the number of Virtuoso Server processes running on each cluster node. One instance per cluster node will work better than four instances per cluster node. You will have more OS resources available as the Virtuoso instances are reduced. Ideally, you want to spread the instances over distinct machines so that you have resources pooled across those machines.
Clustering
When will federation of triple stores be available in Virtuosoand how does it compare to clustering?
Virtuoso has supported Federated SPARQL a/k/a SPARQL-FED since the specification was created. Clustering has more to do with horizontal partitioning of the database across many machines (physical or virtual) to parallelize execution of queries, etc. SPARQL-FED may be used with a Virtuoso Cluster, just as with a Single-Server Instance.