In fact, you will not find a clear answer to this question? That is, when should you use the Shared Server? Also, how many Dispatchers and Shared Servers should be running if the database is configured in Shared Server mode?

As a database administrator, you need to set budgets to make the appropriate decision. You are bound by a certain amount of resources, and at the same time, you are required to provide access to a certain number of users without delay.

In general, the database administrator must coordinate with the system administrator to make the appropriate decision. Now let's assume that you have run the database in Shared Server mode. You can bypass the connection to the database through this mode or if you wish, through the Dedicated Server, by connecting to the database Locally from the same machine that has the database, i.e. without going through the Listener, because the connection is made directly to the database and without using tnsnames.ora which

redirects you to the listener that works on the Shared Server.

SQL> CONN SYS/SYS AS SYSDBA

You can also connect to the database as a Dedicated Server even if the database is running in Shared Server mode by configuring the tnsnames file.

If you connect to the database through the ORCL alias, the connection will be made through the Dedicated Server.SQL> CONN SYSTEM/SYS@ORCL

If the connection is made through the nickname TEST, the connection will be made through the Shared Server.

SQL> CONN SYSTEM/SYS@TEST

Of course, the instance can be returned to work in Dedicated Server mode again by doing the following:

ALTER SYSTEM SET DISPATCHERS='' SCOPE=SPFILE;
ALTER SYSTEM SET SHARED_SERVERS=0 scope=spfile;

It is also worth noting that it is better to perform the tasks of the database administrator, such as completing backup and recovery operations or creating indexes, via the Dedicated Server. Some tasks such as starting and closing the database cannot be performed through this model (Shared Server), so the database administrator performs his tasks through the Dedicated Server.

To inquire:

V$CIRCUIT

V$DISPATCHERS

V$SHARED_SERVER

V$SHARED_SERVER_MONITOR