The frequency and thresholds defined for a rule are default
recommendations. To edit these properties, choose the
Create/Edit Rule link.
The following image shows the screen used to edit rules:
Beside the rule name is the
list box, used for setting the advisor group. This list box shows
existing groupings and any you have added. The
Expression textarea shows the advisor rule,
Variable Assignment the data item associated
with variable(s) used in the rule and
Thresholds determines when to trigger each
The three levels of
Critical Alert indicating increasing levels
of severity. Levels can be triggered by the expression result
being equal to a certain value, greater than a certain value, or
less than a certain value.
The data items that variables are associated with are operating
system (OS) properties such as available RAM or MySQL
characteristics such as the InnoDB buffer pool. To see all
available data items drop down the
list box. For a listing of these data items see
Appendix D, Data Collection Items.
In Figure 2.5, “MySQL Enterprise Monitor User Interface: Editing Rules”, the drop-down
Data Item list box within the
Assignment frame shows the various MySQL server status
or operating system specific variables that you can use in
expressions. The text boxes below
define the levels at which informational, warning, or critical
alerts are issued.
To lower the threshold for an informational alert, simply increase
the number given in the
Info Alert text box.
When a data item can apply to multiple objects, specify through
Instance text box which instance to use for
that item. In almost all cases, set this value to
local. The exceptions are as follows:
For CPU-related items set Instance to
cpu0. Additional CPUs on a system are
referred to as
cpu1, cpu2 and so on.
There can be multiple disks mounted on a system. To refer to
a specific drive, set Instance to the
name of the mounted drive. On Windows this would be
C:, D:, and so on. On Unix systems, use
whatever is valid for the df command.
For RAM-related items set Instance to
Where there are table-specific variables, specify the database name and table name in the Instance text box. This topic is discussed in detail in the following section.
It is not possible to have a data item that is unrelated to an
instance. This raises the error,
You must map
"<variable>" to an instance, and you cannot save
Since an agent can only collect data from one MySQL server, the
instance entry for a variable in a rule does
not need to specify which MySQL server to use; no matter how many
servers are being monitored, there is always a one-to-one
relationship between an agent and its monitored server.
However, on one server there could be multiple occurrences of a
variable. For example, there are multiple possible occurrences of
table-specific variables such as
because there can be multiple databases and tables defined in a
MySQL server. In this case, the “instance” refers to
the database and table that a data item should be associated with,
specified in the form
So, for example, if you want to reference the
Avg_row_length of the
user table in an expression, select
mysql:tablestatus:Avg_row_length from the
Data Item list box and specify
mysql.user in the Instance
On the other hand, in the case of a global server variable, there
is only one possible target. For example, there can only be one
delay_key_write because this
variable is global and applies to the server as a whole. In this
local in the
Instance text box.
To save your changes click the save button at the bottom of the page.
You can change only the thresholds and the frequency of built-in rules. So that rules function properly when updated, other changes are prohibited.
Should you wish to make other changes to a built-in rule, copy it and modify it as desired.
You can edit a rule even if it is currently scheduled. Your
changes are preserved when new rules are imported using the
Check for Updates link.