JDBC Multi Data Sources

A multi data source is an abstraction around a group of data sources that provides load balancing or failover processing between the data sources associated with the multi data source. 


Multi data sources are bound to the JNDI tree or local application context just like data sources are bound to the JNDI tree. 


Applications lookup a multi data source on the JNDI tree or in the local application context just like they do for data sources, and then request a database connection. 


The multi data source determines which data source to use to satisfy the request depending on the algorithm selected in the multi data source configuration: load balancing or failover.


Failover


The Failover algorithm provides an ordered list of data sources to use to satisfy connection requests. 


( 1 ) Normally, every connection request to this kind of multi data source is served by the first data source in the 
       list.


(2 )  If a database connection test fails and the connection cannot be replaced, or if the data source is suspended, 
       a connection is sought sequentially from the next data source on the list.


Note :- 


This algorithm relies on Test Reserved Connections (TestConnectionsOnReserve) on the data source to test a connection in the first data source to see if the data source is healthy. If the connection fails the test, the multi data source uses a connection from the next data source listed in the multi data source


Select Services -> Multi Data Source then New

 Enter name for Multi Data source & JNDI name, Select algo type Failover or Load Balancing

 

 Select Target

 Select driver type XA

 Select the Data Sources which you want to assign to this Data Source & finish

final