ORACLE: the client automatically selects valid connection addresses, automatic session reconnection, and Server Load balancer

 

This is a feature of the Oracle client, is for the ApplicationProgramProvides driver-level ha functions. You can directly configure it in tnsnames. ora, which is very convenient!

1. The client automatically selects a valid connection address

When there are multiple addresses, We can configure the Oracle client to try each address one by one until the available address is found!

(

(Source_route = on) # instructs the Oracle client to try to connect one by one until available addresses are found. Otherwise, only the first address is used.

(Address = (Protocol = TCP) (host = IP-1) (Port = 1521 ))

(Address = (Protocol = TCP) (host = IP-2) (Port = 1521 ))

....

)

 

Ii. Automatic reconnection of client sessions

When there are multiple addresses, We can configure the Oracle client to try each address one by one until the available address is found!

(

(Failover =On)# Indicates that Oracle customers can perform session reconnection. This function is enabled by default, but the reconnection mode is type = none, which means that the Failover function is not enabled. You must set the CONNECT_DATA parameter !!

(Address = (Protocol = TCP) (host = IP-1) (Port = 1521 ))

(Address = (Protocol = TCP) (host = IP-2) (Port = 1521 ))

....

(CONNECT_DATA =

(SERVICE_NAME = Service)

(Failover_mode =

(Type = {None| Session | select}) # function level of session reconnection.

(Method = {Basic| Preconnect}) # is the connection established during failover or in advance?

(Retries = 5) # Number of Retries

(Delay = 1) # retry Delay

)

)

 

Three Oracle clients support connection to Server Load balancer at the same time

(

(Load_balance = on) # instruct the Oracle client to perform Load Balancing for connection sessions

(Address = (Protocol = TCP) (host = IP-1) (Port = 1521 ))

(Address = (Protocol = TCP) (host = IP-2) (Port = 1521 ))

....

)