MetricDataQuery
This structure is used in both GetMetricData
and PutMetricAlarm
. The supported
use of this structure is different for those two operations.
When used in GetMetricData
, it indicates the metric data to return, and whether this call is just retrieving
a batch set of data for one metric, or is performing a math expression on metric
data. A
single GetMetricData
call can include up to 100 MetricDataQuery
structures.
When used in PutMetricAlarm
, it enables you to create an alarm based on a
metric math expression. Each MetricDataQuery
in the array specifies either
a metric to retrieve, or a math expression to be performed on retrieved metrics.
A
single PutMetricAlarm
call can include up to 20
MetricDataQuery
structures in the array. The 20 structures can include
as many as 10 structures that contain a MetricStat
parameter to retrieve a
metric, and as many as 10 structures that contain the Expression
parameter
to perform a math expression. Of those Expression
structures, one must have True
as the value for ReturnData
. The result of this expression is the value the alarm watches.
Any expression used in a PutMetricAlarm
operation must return a single time series. For more information, see Metric Math Syntax and Functions in the Amazon CloudWatch User
Guide.
Some of the parameters of this structure also have different uses whether you are
using this structure in a GetMetricData
operation or a PutMetricAlarm
operation. These differences are explained in the following parameter list.
Contents
 Expression

The math expression to be performed on the returned data, if this object is performing a math expression. This expression can use the
Id
of the other metrics to refer to those metrics, and can also use theId
of other expressions to use the result of those expressions. For more information about metric math expressions, see Metric Math Syntax and Functions in the Amazon CloudWatch User Guide.Within each MetricDataQuery object, you must specify either
Expression
orMetricStat
but not both.Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Required: No
 Id

A short name used to tie this object to the results in the response. This name must be unique within a single call to
GetMetricData
. If you are performing math expressions on this set of data, this name represents that data and can serve as a variable in the mathematical expression. The valid characters are letters, numbers, and underscore. The first character must be a lowercase letter.Type: String
Length Constraints: Minimum length of 1. Maximum length of 255.
Required: Yes
 Label

A humanreadable label for this metric or expression. This is especially useful if this is an expression, so that you know what the value represents. If the metric or expression is shown in a CloudWatch dashboard widget, the label is shown. If Label is omitted, CloudWatch generates a default.
Type: String
Required: No
 MetricStat

The metric to be returned, along with statistics, period, and units. Use this parameter only if this object is retrieving a metric and not performing a math expression on returned data.
Within one MetricDataQuery object, you must specify either
Expression
orMetricStat
but not both.Type: MetricStat object
Required: No
 ReturnData

When used in
GetMetricData
, this option indicates whether to return the timestamps and raw data values of this metric. If you are performing this call just to do math expressions and do not also need the raw data returned, you can specifyFalse
. If you omit this, the default ofTrue
is used.When used in
PutMetricAlarm
, specifyTrue
for the one expression result to use as the alarm. For all other metrics and expressions in the samePutMetricAlarm
operation, specifyReturnData
as False.Type: Boolean
Required: No
See Also
For more information about using this API in one of the languagespecific AWS SDKs, see the following: