[comment]: # translation:outdated [comment]: # ({new-ee60e21e}) # 1 Aggregate functions Except where stated otherwise, all functions listed here are supported in: - [Trigger expressions](/manual/config/triggers/expression) - [Calculated items](/manual/config/items/itemtypes/calculated) Aggregate functions can work with either: - history of items, for example, `min(/host/key,1h)` - [foreach functions](/manual/appendix/functions/aggregate/foreach) as the only parameter, for example, `min(last_foreach(/*/key))` Some general notes on function parameters: - Function parameters are separated by a comma - Optional function parameters (or parameter parts) are indicated by `<` `>` - Function-specific parameters are described with each function - `/host/key` and `(sec|#num)<:time shift>` parameters must never be quoted [comment]: # ({/new-ee60e21e}) [comment]: # ({new-4d343eb8}) ##### Common parameters - `/host/key` is a common mandatory first parameter for the functions referencing the host item history - `(sec|#num)<:time shift>` is a common second parameter for the functions referencing the host item history, where: - **sec** - maximum [evaluation period](/manual/config/triggers#evaluation_period) in seconds (time [suffixes](/manual/appendix/suffixes) can be used), or - **\#num** - maximum [evaluation range](/manual/config/triggers#evaluation_period) in latest collected values (if preceded by a hash mark) - **time shift** (optional) allows to move the evaluation point back in time. See [more details](/manual/config/triggers/expression#time_shift) on specifying time shift. [comment]: # ({/new-4d343eb8}) [comment]: # ({new-ad86e84b}) #### Aggregate functions |FUNCTION|<|<|<| |--------|-|-|-| |<|**Description**|**Function-specific parameters**|**Comments**| |**avg** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Average value of an item within the defined evaluation period.|See [common parameters](#common-parameters).|Supported value types: float, int

Examples:
=> **avg**(/host/key,**1h**) → average value for the last hour until [now](/manual/config/triggers#evaluation_period)
=> **avg**(/host/key,**1h:now-1d**) → average value for an hour from 25 hours ago to 24 hours ago from [now](/manual/config/triggers#evaluation_period)
=> **avg**(/host/key,**\#5**) → average value of the five latest values
=> **avg**(/host/key,**\#5:now-1d**) → average value of the five latest values excluding the values received in the last 24 hours

Time shift is useful when there is a need to compare the current average value with the average value some time ago.| |**bucket\_percentile** (item filter,time period,percentage)|<|<|<| |<|Calculates the percentile from the buckets of a histogram.|**item filter** - see [item filter](/manual/appendix/functions/aggregate/foreach#item_filter)
**time period** - see [time period](/manual/appendix/functions/aggregate/foreach#time_period)
**percentage** - percentage (0-100)|Supported only in calculated items.

This function is an alias for `histogram_quantile(percentage/100, bucket_rate_foreach(item filter, time period, 1))`| |**count** (func\_foreach(item filter,))|<|<|<| |<|Count of values in an array returned by a foreach function.|**func\_foreach** - foreach function for which the number of returned values should be counted (with supported arguments). See [foreach functions](/manual/appendix/functions/aggregate/foreach) for details.|Supported value type: int

Example:
=> **count**(max\_foreach(/\*/net.if.in\[\*\],1h)) → number of net.if.in items that received data in the last hour until [now](/manual/config/triggers#evaluation_period)

Note that using **count()** with a history-related foreach function (max\_foreach, avg\_foreach, etc.) may lead to performance implications, whereas using **exists\_foreach()**, which works only with configuration data, will not have such effect.| |**histogram\_quantile** (quantile,bucket1,value1,bucket2,value2,...)|<|<|<| |<|Calculates the φ-quantile from the buckets of a histogram.|**quantile** - 0 ≤ φ ≤ 1
**bucketN, valueN** - manually entered pairs (>=2) of parameters or response of [bucket\_rate\_foreach](/manual/appendix/functions/aggregate/foreach)|Supported only in calculated items.

Functionally corresponds to '[histogram\_quantile](https://prometheus.io/docs/prometheus/latest/querying/functions/#histogram_quantile)' of PromQL.

Returns -1 if values of the last 'Infinity' bucket (*"+inf"*) are equal to 0.

Example:
=> **histogram\_quantile**(0.75,1.0,last(/host/rate\_bucket\[1.0\]),"+Inf",last(/host/rate\_bucket\[Inf\])
=> **histogram\_quantile**(0.5,bucket\_rate\_foreach(//item\_key,30s))| |**item\_count** (item filter)|<|<|<| |<|Count of existing items in configuration that match filter criteria.|**item filter** - criteria for item selection, allows referencing by host group, host, item key, and tags. Wildcards are supported. See [item filter](/manual/appendix/functions/aggregate/foreach#item_filter) for more details.|Supported value type: int

Works as an alias for the *count(exists\_foreach(item\_filter))* function.

Example:
=> **item\_count**(/\*/agent.ping?\[group="Host group 1"\]) → number of hosts with the *agent.ping* item in the "Host group 1"| |**kurtosis** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|"Tailedness" of the probability distribution in collected values within the defined evaluation period.

See also: [Kurtosis](https://en.wikipedia.org/wiki/Kurtosis)|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **kurtosis**(/host/key,**1h**) → kurtosis for the last hour until [now](/manual/config/triggers#evaluation_period)| |**mad** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Median absolute deviation in collected values within the defined evaluation period.

See also: [Median absolute deviation](https://en.wikipedia.org/wiki/Median_absolute_deviation)|See [common-parameters](#common parameters).|Supported value types: float, int

Example:
=> **mad**(/host/key,**1h**) → median absolute deviation for the last hour until [now](/manual/config/triggers#evaluation_period)| |**max** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Highest value of an item within the defined evaluation period.|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **max**(/host/key,**1h**) - **min**(/host/key,**1h**) → calculate the difference between the maximum and minimum values within the last hour until [now](/manual/config/triggers#evaluation_period) (delta of values)| |**min** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Lowest value of an item within the defined evaluation period.|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **max**(/host/key,**1h**) - **min**(/host/key,**1h**) → calculate the difference between the maximum and minimum values within the last hour until [now](/manual/config/triggers#evaluation_period) (delta of values)| |**skewness** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Asymmetry of the probability distribution in collected values within the defined evaluation period.

See also: [Skewness](https://en.wikipedia.org/wiki/Skewness)|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **skewness**(/host/key,**1h**) → skewness for the last hour until [now](/manual/config/triggers#evaluation_period)| |**stddevpop** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Population standard deviation in collected values within the defined evaluation period.

See also: [Standard deviation](https://en.wikipedia.org/wiki/Standard_deviation)|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **stddevpop**(/host/key,**1h**) → population standard deviation for the last hour until [now](/manual/config/triggers#evaluation_period)| |**stddevsamp** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Sample standard deviation in collected values within the defined evaluation period.

See also: [Standard deviation](https://en.wikipedia.org/wiki/Standard_deviation)|See [common parameters](#common-parameters).|Supported value types: float, int

At least two data values are required for this function to work.

Example:
=> **stddevsamp**(/host/key,**1h**) → sample standard deviation for the last hour until [now](/manual/config/triggers#evaluation_period)| |**sum** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Sum of collected values within the defined evaluation period.|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **sum**(/host/key,**1h**) → sum of values for the last hour until [now](/manual/config/triggers#evaluation_period)| |**sumofsquares** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|The sum of squares in collected values within the defined evaluation period.|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **sumofsquares**(/host/key,**1h**) → sum of squares for the last hour until [now](/manual/config/triggers#evaluation_period)| |**varpop** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Population variance of collected values within the defined evaluation period.

See also: [Variance](https://en.wikipedia.org/wiki/Variance)|See [common parameters](#common-parameters).|Supported value types: float, int

Example:
=> **varpop**(/host/key,**1h**) → population variance for the last hour until [now](/manual/config/triggers#evaluation_period)| |**varsamp** (/host/key,(sec\|\#num)<:time shift>)|<|<|<| |<|Sample variance of collected values within the defined evaluation period.

See also: [Variance](https://en.wikipedia.org/wiki/Variance)|See [common parameters](#common-parameters).|Supported value types: float, int

At least two data values are required for this function to work.

Example:
=> **varsamp**(/host/key,**1h**) → sample variance for the last hour until [now](/manual/config/triggers#evaluation_period)| [comment]: # ({/new-ad86e84b})