Frequently Asked Questions

 Virtuoso Universal Server

query
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atext
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.5852d22ea64af628edd40492cacdcaf4
#5852d22ea64af628edd40492cacdcaf4
ABAC
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#abdc72442c6c3a7927a42ccd38932a24
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.
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.7e2a95d335234fdb343a511e8b5eecea
#7e2a95d335234fdb343a511e8b5eecea
Conceptual Data Virtualization
8addf30978b4a51d962cacde58adb6e8
#8addf30978b4a51d962cacde58adb6e8
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.
ca05b99ca51143a568fba24c7eb5676b
.ca05b99ca51143a568fba24c7eb5676b
#ca05b99ca51143a568fba24c7eb5676b
Conceptual Data Virtualization
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#8addf30978b4a51d962cacde58adb6e8
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.
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.8d1c761716a78b750b638a66920ad696
#8d1c761716a78b750b638a66920ad696
Conceptual Data Virtualization
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#8addf30978b4a51d962cacde58adb6e8
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.
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.089fa2e983f8c80ceccfbab5fb9ecc43
#089fa2e983f8c80ceccfbab5fb9ecc43
Data Virtualization
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#329190f5958cf6cf5c10e3ec2267a7e9
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.)
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.7e2a95d335234fdb343a511e8b5eecea
#7e2a95d335234fdb343a511e8b5eecea
Data Virtualization
329190f5958cf6cf5c10e3ec2267a7e9
#329190f5958cf6cf5c10e3ec2267a7e9
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.
ca05b99ca51143a568fba24c7eb5676b
.ca05b99ca51143a568fba24c7eb5676b
#ca05b99ca51143a568fba24c7eb5676b
Data Virtualization
329190f5958cf6cf5c10e3ec2267a7e9
#329190f5958cf6cf5c10e3ec2267a7e9
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.
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.8d1c761716a78b750b638a66920ad696
#8d1c761716a78b750b638a66920ad696
Data Virtualization
329190f5958cf6cf5c10e3ec2267a7e9
#329190f5958cf6cf5c10e3ec2267a7e9
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.
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.c806ce92b383351948caa184db2cba42
#c806ce92b383351948caa184db2cba42
Cluster Module
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#29f121f7ec95df55147ad145d1765bcb
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.
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.2a27fd3f8727a1418fff0b9cdad41382
#2a27fd3f8727a1418fff0b9cdad41382
Cluster Module
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#29f121f7ec95df55147ad145d1765bcb
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).
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#325856d8118301b8adb14c4338aa5cee
Cluster Module
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#29f121f7ec95df55147ad145d1765bcb
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.
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#a1231996afca3ef3e9a6c33781e1e141
Cluster Module
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#29f121f7ec95df55147ad145d1765bcb
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.
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#8d2e4ce1d86c6bcaee5b71219e3a69d5
Cluster Module
29f121f7ec95df55147ad145d1765bcb
#29f121f7ec95df55147ad145d1765bcb
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.
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.5852d22ea64af628edd40492cacdcaf4
#5852d22ea64af628edd40492cacdcaf4
Virtuoso Cluster
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#834e673b2d09085ab051c8cf75e20e05
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.
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.c806ce92b383351948caa184db2cba42
#c806ce92b383351948caa184db2cba42
Virtuoso Cluster
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#834e673b2d09085ab051c8cf75e20e05
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.
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.2a27fd3f8727a1418fff0b9cdad41382
#2a27fd3f8727a1418fff0b9cdad41382
Virtuoso Cluster
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#834e673b2d09085ab051c8cf75e20e05
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).
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#325856d8118301b8adb14c4338aa5cee
Virtuoso Cluster
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#834e673b2d09085ab051c8cf75e20e05
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.
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#a1231996afca3ef3e9a6c33781e1e141
Virtuoso Cluster
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#834e673b2d09085ab051c8cf75e20e05
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.
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#8d2e4ce1d86c6bcaee5b71219e3a69d5
Virtuoso Cluster
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#834e673b2d09085ab051c8cf75e20e05
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.
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#c806ce92b383351948caa184db2cba42
Virtuoso Cluster Node (VCN)
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#a19940f2ae9d6370afab9b8ecc0f8ce6
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.
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.325856d8118301b8adb14c4338aa5cee
#325856d8118301b8adb14c4338aa5cee
Virtuoso Cluster Node (VCN)
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#a19940f2ae9d6370afab9b8ecc0f8ce6
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.
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.5852d22ea64af628edd40492cacdcaf4
#5852d22ea64af628edd40492cacdcaf4
Virtuoso Replication Cluster
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#e91900f75ae8546b1cdd32e3c0ba55f5
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.
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#2a27fd3f8727a1418fff0b9cdad41382
Virtuoso Replication Cluster
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#e91900f75ae8546b1cdd32e3c0ba55f5
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).
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#5852d22ea64af628edd40492cacdcaf4
Virtuoso Server Instance (VSI)
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#bfbcdc32abbe33e2be8b0525d7e70b07
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.
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#c806ce92b383351948caa184db2cba42
Virtuoso Server Instance (VSI)
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#bfbcdc32abbe33e2be8b0525d7e70b07
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.
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.2a27fd3f8727a1418fff0b9cdad41382
#2a27fd3f8727a1418fff0b9cdad41382
Virtuoso Server Instance (VSI)
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#bfbcdc32abbe33e2be8b0525d7e70b07
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).
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Virtuoso Server Instance (VSI)
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#bfbcdc32abbe33e2be8b0525d7e70b07
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.
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Virtuoso Server Instance (VSI)
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#bfbcdc32abbe33e2be8b0525d7e70b07
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.
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.5852d22ea64af628edd40492cacdcaf4
#5852d22ea64af628edd40492cacdcaf4
Virtuoso Shared-Nothing Cluster
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#6f86259ec59e66ee79d528c4d81ac3e8
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.
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.c806ce92b383351948caa184db2cba42
#c806ce92b383351948caa184db2cba42
Virtuoso Shared-Nothing Cluster
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#6f86259ec59e66ee79d528c4d81ac3e8
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.
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.2a27fd3f8727a1418fff0b9cdad41382
#2a27fd3f8727a1418fff0b9cdad41382
Virtuoso Shared-Nothing Cluster
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#6f86259ec59e66ee79d528c4d81ac3e8
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).
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#325856d8118301b8adb14c4338aa5cee
Virtuoso Shared-Nothing Cluster
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#6f86259ec59e66ee79d528c4d81ac3e8
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.
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#a1231996afca3ef3e9a6c33781e1e141
Virtuoso Shared-Nothing Cluster
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#6f86259ec59e66ee79d528c4d81ac3e8
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.
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#8d2e4ce1d86c6bcaee5b71219e3a69d5
Virtuoso Shared-Nothing Cluster
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#6f86259ec59e66ee79d528c4d81ac3e8
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.
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#089fa2e983f8c80ceccfbab5fb9ecc43
Java Database Connectivity (JDBC)
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#a1049f911c79b2d649230f6ade83746c
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.)
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.7e2a95d335234fdb343a511e8b5eecea
#7e2a95d335234fdb343a511e8b5eecea
Java Database Connectivity (JDBC)
a1049f911c79b2d649230f6ade83746c
#a1049f911c79b2d649230f6ade83746c
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.
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.ca05b99ca51143a568fba24c7eb5676b
#ca05b99ca51143a568fba24c7eb5676b
Java Database Connectivity (JDBC)
a1049f911c79b2d649230f6ade83746c
#a1049f911c79b2d649230f6ade83746c
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.
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.8d1c761716a78b750b638a66920ad696
#8d1c761716a78b750b638a66920ad696
Java Database Connectivity (JDBC)
a1049f911c79b2d649230f6ade83746c
#a1049f911c79b2d649230f6ade83746c
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.
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#34be5feb64aee71dc9390d611cf27702
Linked Data
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#cce86c220fbc6693ae48f216761d99ab
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.
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#ba3a66c11bda986f85c105eb11e3a66b
Linked Data
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#cce86c220fbc6693ae48f216761d99ab
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.
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#e77d7dc002f55185d645ec475d3d3cc4
Linked Data
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#cce86c220fbc6693ae48f216761d99ab
How do I install and configure the Virtuoso Faceted Browser?
See required prerequisites, pre-installation steps, VAD package installation, post-installation stepsand example tutorials.
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Linked Data
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#cce86c220fbc6693ae48f216761d99ab
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.
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NewSQL
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Is Virtuoso currently evaluating NoSQL database for the storage of quads?
Virtuoso is a Native Hybrid DBMS — it is SQL and NoSQL combined.
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NoSQL
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Is Virtuoso currently evaluating NoSQL database for the storage of quads?
Virtuoso is a Native Hybrid DBMS — it is SQL and NoSQL combined.
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Open Database Connectivity (ODBC)
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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.)
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Open Database Connectivity (ODBC)
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#62b65d65c41ec58d7ab21331cd733080
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.
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Open Database Connectivity (ODBC)
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#62b65d65c41ec58d7ab21331cd733080
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.
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#8d1c761716a78b750b638a66920ad696
Open Database Connectivity (ODBC)
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#62b65d65c41ec58d7ab21331cd733080
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.
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#7e2a95d335234fdb343a511e8b5eecea
SQL Relational Tables to RDF Property (Predicate) Graph Mapping Language
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#756a2bab8dcd2dd3ab8b22009d3f2bce
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.
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#ca05b99ca51143a568fba24c7eb5676b
SQL Relational Tables to RDF Property (Predicate) Graph Mapping Language
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#756a2bab8dcd2dd3ab8b22009d3f2bce
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.
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.8d1c761716a78b750b638a66920ad696
#8d1c761716a78b750b638a66920ad696
SQL Relational Tables to RDF Property (Predicate) Graph Mapping Language
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#756a2bab8dcd2dd3ab8b22009d3f2bce
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.
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SPARQL
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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.
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#8d2e4ce1d86c6bcaee5b71219e3a69d5
SPARQL
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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.
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Federated SPARQL
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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.
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Federated SPARQL
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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.
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SPARQL Query Language
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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.
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SQL Relational Database Management System
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Is Virtuoso currently evaluating NoSQL database for the storage of quads?
Virtuoso is a Native Hybrid DBMS — it is SQL and NoSQL combined.
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#5852d22ea64af628edd40492cacdcaf4
Clustering
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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.
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Clustering
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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.
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Clustering
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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).
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Clustering
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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.
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Clustering
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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.
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Clustering
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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.