Autonomous Database uses DNS names that map to multiple IP addresses (multiple load balancers) for better availability and performance. Depending on your application, you may want to configure certain JVM networking properties.

For the Java Virtual Machine (JVM) address cache, any address resolution attempt caches the result whether it was successful or not, so that subsequent identical requests do not have to access the naming service. The address cache properties allow you to tune how the cache operates. In particular, the networkaddress.cache.ttl value specifies the number of seconds a successful name lookup is kept in the cache. A value of -1, the default value, indicates a “cache forever” policy, while a value of 0 (zero) means no caching.

If your Java Virtual Machine (JVM) is configured to cache DNS address lookups, your application may be using only one IP address to connect to your Autonomous Database, resulting in lower throughput. To prevent this you can change your JVM's networkaddress.cache.ttl value to 0, so that every connection request does a new DNS lookup. This ensures that different threads in your application are distributed over multiple load balancers.

To change the networkaddress.cache.ttl value for all applications, or in your application, do one of the following:

• Configure the security policy to set the value for all applications:

  Set networkaddress.cache.ttl=0 in the file $JAVA_HOME/jre/lib/security/java.security

• Set the following property in your application code:

  java.security.Security.setProperty("networkaddress.cache.ttl" , "0");