客户端连接服务器时,如果在sqlnet.ora中配置了本地命名,则登陆过程中会先去读取tnsnames文件.
这是一个连接rac的连接示例
test =
  (DESCRIPTION =
  (load_balance = yes)
  (failover = on)
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.2)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.3)(PORT = 1521))
    )
    (CONNECT_DATA =
        (SERVICE_NAME = test)
        (SERVER = DEDICATED)
        (failover_mode=(type=select)(method=preconnect)(retries=20)(delay=20))
    )
  )
 
test1 =
   (DESCRIPTION =
     (ADDRESS_LIST =
       (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.2)(PORT = 1521))
       )
       (CONNECT_DATA =
         (SERVICE_NAME = test)
         (INSTANCE_NAME = test1)
       )
   )

test2=
   (DESCRIPTION =
     (ADDRESS_LIST =
       (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.3)(PORT = 1521))
       )
       (CONNECT_DATA =
         (SERVICE_NAME = test)
         (INSTANCE_NAME = test2)
       )
   )
)