7.8.Virtuoso Data Access Clients Connection
Fail over and Load Balancing Support
The Virtuoso Data Access Clients ODBC, JDBC, ADO.Net, OLE DB,
Sesame, Jena and Redland as of Release 6.1 and above support round
robin connections to Virtuoso server instances enabling server fail
over, load balancing and fault tolerant connections to be performed
across multiple server instances configured in a cluster or as
separate server instances.
Fail over connections are enabled by specifying a comma
delimited list of servers to failover to, in the "Host" or 'Server"
connect string attribute, with the list being worked through in the
order presented to determine which Virtuoso Server instance is
used. A Round robin (load balanced) connection can be configured by
adding the connect string attribute "RoundRobin" = [True | Yes |
False | No], in which case the server for the connection is chosen
at random from the comma delimited provided as for a Failover
Example connect strings for Virtuoso ODBC, JDBC, ADO.Net and OLE
DB driver/providers are provided below. The Virtuoso Sesame and
Jena providers which make use of the JDBC driver and Redland
Provider which makes use of the ODBC driver, would simply make use
of a suitably configured JDBC or ODBC connect string to enable
Failover or Round Robin connections to be made with them.