As far as  I understand, setting monitor switches at the instance level
affectes all databases under the instance's control. That means every
applications that establishes a connection to a database under the
instance's control will inherit the switch settings made in the
instance's configuration.

While setting monitor switches at the application level only affects
the database a single application which is connecting with.

Mike Li
MIT -- May Dept Store DBA

The database manager monitor switch configuration parameters
(DFT_MON_BUFPOOL, etc) simply control the _default_ setting for
each particular monitor switch when an application attaches to
the instance.

For example, the default for V8 is to have only DFT_MON_TIMESTAMP
on.  Therefore, when you first attach to an instance, issue the
GET MONITOR SWITCHES command and you'll see:

Buffer Pool Activity Information  (BUFFERPOOL) = OFF
Lock Information                        (LOCK) = OFF
Sorting Information                     (SORT) = OFF
SQL Statement Information          (STATEMENT) = OFF
Table Activity Information             (TABLE) = OFF
Take Timestamp Information         (TIMESTAMP) = ON  11/23/2005
14:36:48.039143
Unit of Work Information                 (UOW) = OFF

If DFT_MON_BUFPOOL was ON, then you would also see the BUFFERPOOL
switch on, too.

You can turn on the switches manually (e.g., UPDATE MONITOR SWITCHES
USING SORT ON).

It's also important to understand that the state of the monitor
switches are specific to each instance attachment.  So one attachment
can have the BUFFERPOOL monitor switch enabled, but another one can
have it off, regardless of the setting of DFT_MON_BUFPOOL.