Same listener for 2 databases

Question

Hi,
i installed oracle EM GRID CONSOLE on my linux system with database called "emrep"
and then i installed another database "orcl"
now when i log into grid console and i view my targets i see only one listener
called "LISTENER0_oracle.ebenezer.com"
and when i see the serviced databases for this listener, i see both the databases under this listener.
does this mean that one listener in one system is all required to service how many databases as possible.
or do we need one unique listener for each database. if then how can i create unique listeners.
Can someone help me please.
Thanks,
Philip.

Answer 1

Philip,
I will try to answer at your questions.
so from what u r saying is, if i have 3 databases in
my linux system under different oracle_homes.
all i need is one listener.ora file and have all 3
databases start under this one file. and i can delete
the other 2 listener.ora files, because i dont need
them at all.For this, my answer is a question : why have different ORACLE_HOME if databases are in same version ? This is Ok when database are in different oracle version.
1. if i want to know how many listeners are in setup...You can see it with lsnrctl command, after set well ORACLE_HOME (for linux, export ...) :
set ORACLE_HOME=e:\oracle\ora92
E:\oracle\ora92\bin>lsnrctl status
LSNRCTL for 32-bit Windows: Version 9.2.0.7.0 - Production on 16-NOV-2005 22:44:
41
Copyright (c) 1991, 2002, Oracle Corporation.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=gocha)(PORT=1522)))
STATUS of the LISTENER
Alias                     LISTENER
Version                   TNSLSNR for 32-bit Windows: Version 9.2.0.7.0 - Produc
tion
Start Date                16-NOV-2005 22:44:04
Uptime                    0 days 0 hr. 0 min. 40 sec
Trace Level               off
Security                  OFF
SNMP                      OFF
Listener Parameter File   E:\oracle\ora92\network\admin\listener.ora
Listener Log File         E:\oracle\ora92\network\log\listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=gocha)(PORT=1522)))
Services Summary...
Service "demo9i" has 1 instance(s).
  Instance "demo9i", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
E:\oracle\ora92\bin>>
2. when i create a listener using net configuartion...For my part, manually seems the only one solution in your case.
>
3.when i have 3 databases and i when i login through...When you are logon to database, you can see what db with
select * from v$instance;But to connect to an other db, you need first set as well your ORACLE_SID
export ORACLE_SID=emrep
sqlplus '/ as sysdba'>
4. when i create a database by default the listener...Default name is well in most of case, but you can give a name to know the environment (like LISTENER_DEV, LISTENER_PROD...)
Perhaps you need to read some Oracle docs. You can find here http://www.oracle.com/pls/db102/portal.portal_db?selected=1 too many docs, I can advise you to read 2 Day DBA to start as well your dba life.
Good luck in your job,
Nicolas.