Oracle Listener Service Registration Oracle Tips by Burleson Consulting

Question: I have restored my QAS database and filesystem from my backup tape, and have checked all the configuration files and oracle setting files and do not notice any problem.  But when I try to start my listener, I just get error messages.  Why?

 

Answer: This is a feature where the PMON process dynamically registers instance information with a listener.  With that, the listener then forwards client connection requests to the appropriate service handler.  The listener is provided with information from PMON about the names of the database services provided by the database, the name of the database instance associated with the services and its current and maximum load, and information on the service handlers (dispatchers and dedicated servers).  That information includes what service handlers are available for the instance and their type, protocol addresses, and their current and maximum loads.

Service registration is dynamic, thereby reducing the administrative overhead for multiple databases and instances, and it does not require configuration in the listener.ora file.  

The services an instance belongs to are listed by the SERVICE_NAMES initialization parameter. Each instance registers with the listeners of other instances belonging to the same services on startup.  During database operations, the instances of each service pass information about CPU use and the current connection communicates by counts to all listeners in the same services, enabling dynamic load balancing and connection failover.

This was the question asked by one of our Oracle Forum members recently.  Please visit the forum at dbaforums.org/oracle/

 

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