This screen displays the actual database parameter and attribute
settings being used by the processes attached to the database.
Optionally, users are allowed to dynamically update certain
database parameters and attributes on a single node at run time.
The net effect of these changes can be examined at run time
without having to restart database processes. These updates are
nonpersistent.
For example, when the RDM$BIND_BUFFERS logical name is defined
at the process level, there is no method available for the
database administrator (DBA) to examine its setting at runtime.
The same is true for any database logical name and most
interesting database attributes that affect runtime performance
of the database. However, the Database Dashboard provides this
information dynamically.
The Database Dashboard facility allows you to "drive" the
database faster or slower, and immediately see the impact of
increasing or decreasing certain database settings.
You can use the Update menu option, by typing the letter U, to
change the value of a database attribute. Before you can update
database attributes, you need to start your Performance Monitor
session with the Options=Update qualifier and you need OpenVMS
WORLD, BYPASS, and SYSNAM privileges.
CAUTION
You should use the Update option carefully. Oracle Rdb does
not perform error checking on the updated values.
Note that updates made to any attributes are not stored in the
database root file. The purpose of updating attributes is to
test and measure the effects of changes on the database, so that
you can later make persistent changes to appropriate database
attributes using interactive SQL.
Database attributes are updated on the current node only.
You can use the Config menu option, by typing the letter C, to
display the configuration submenu. The configuration submenu
provides the following options:
o Use XXX notification of change
Broadcast the changes to the database attributes and
parameters actively or passively. The option description
changes depending on which method of broadcast is current.
o Notify users of previous changes
Active notification means that all processes attached to the
database on the node will be immediately notified that a database
attribute setting has been modified and that they should reset
their individual parameter values. Passive notification means
that the user processes will be notified passively at intervals
determined by the database software. Passive notification is the
default, as it is non-intrusive to system performance.
The advantage of active notification is that each database user
on the node is immediately notified of the change and that the
new parameter settings are immediately used. The disadvantage
is that system performance may be temporarily impacted while the
users respond to the notification.
The advantage of passive notification is that there is no impact
on the system. The disadvantage is that you have no control over
when the individual processes will be notified that a particular
database parameter setting has changed.
When using passive notification, a broadcast notification can be
performed using the "Notify users of previous changes" option of
the Config submenu.
The Dashboard display contains the following columns:
o Current Value
This column contains the current value for each database
attribute. On global database screens, this is the default
value being used by all processes. On per-process screens,
this is the actual value being used by that particular
process.
o Previous Value
This column contains the previous value for each database
attribute. When a database attribute is dynamically updated,
this column will contain the value before it was modified.
o Lowest Value
This column contains the lowest value for each database
attribute.
o Highest Value
This column contains the highest value for each database
attribute.
o Original Value
This column contains the original value for each database
attribute. This column remains unchanged regardless of the
changes made to the database attribute.
o Chng Cnt
This column contains the count of the number of changes to
each database attribute. On global database screens, this
count is the number of times the particular database attribute
was updated by the user. On per-process screens, this count is
the number of times the actual process has updated its dynamic
information.
The dynamic updates that users make to the database are reflected
only in the Current Value column. The remaining columns reflect
changes made by the current user only.
You can display successive dashboards by pressing the right angle
bracket (>) key or the Next Screen key. To display a previous
dashboard, press the left angle bracket (<) key or the Prev
Screen key. Note that you cannot go to the per-process dashboard
screens.
The Dashboard screen is not recorded in the binary output file
produced using the Output qualifier. Consequently, this display
is not available when you replay a binary file using the Input
qualifier.