Re: 2 Databases. 1 or 2 listeners??

On Tue, 28 Dec 2004 01:52:53 -0800, qazmlp wrote:

> There are 2 databases(1 is for the lower layer modules and another one
> is for pure application layer) running on a Unix server.
>
> I am bit confused whether to have a single Oracle listener on this
> server or to have 2 different listeners, one for each database on the
> server. What exactly is highly recommended? Why?
>
> Could you explain the factors that I have to consider to decide about
> this?
>
> Thanks!

A listener listens on behalf of the machine. It can and will perform the listening function for all the instances registered. Registration is accomplished automatically for newer versions of the datbase or by explicitly being listed in the listener.ora file.

Multiple listeners are recommended only when multiple configurations are required, or there are different admin/maintenance reasons such as independant concurrent _listener_ operation & startup/log/shutdown/ports.

Your question is quite typical of users who do not realize that, for database interaction, the listener's involvement is summarized as

• the listener catches the request
• spawns or requests a database process/thread
• redirects or passes the connection to the process/thread, usually on a different port
• gets out of the way

There are caveats and variations to the above, and a whole pile of capabilities not discussed. But these are most commonly required by organizations advanced enough to read the docco at http://tahiti.oracle.com

So, the direct answer to your question is:

"Use one listener unless you have exceptional circumstances such as extensive use of external processes that you want to manage independantly, mixtures of dedicated and shared servers that you need to start/shut individually, or uncooperative database version issues that might occur due to the differences between SQL*Net and Oracle Networking (which might happen between Oracle 7 and an Oracle 10g) database."

Also, under normal circumstances use the listener for the highest database version.

FGB Received on Tue Dec 28 2004 - 10:14:40 CST