stddev_sample

Learn more about the Cortex Query Language stddev_sample() function used with both comp and windowcomp stages.

Syntax

comp stage

comp stddev_sample(<field>) [as <alias>] by <field_1>,<field_2> [addrawdata = true|false [as <target field>]]

windowcomp stage

windowcomp stddev_sample(<field>) [by <field> [,<field>,...]] [sort [asc|desc] <field1> [, [asc|desc] <field2>,...]] [between 0|null|<number>|-<number> [and 0|null|<number>|-<number>] [frame_type=range]] [as <alias>]

Description

The stddev_sample() function is used to return a single sample (unbiased) standard deviation value of a field for a group of rows. The function syntax and application is based on the preceding stage:

comp stage

When the stddev_sample aggregation function is used with a comp stage, the function returns a single sample (unbiased) standard deviation value of a field over a group of rows, for all records that contain matching values for the fields identified in the by clause.

In addition, you can configure whether the raw data events are displayed by setting addrawdata to either true or false (default), which are used to configure the final comp results. When including raw data events in your query, the query runs for up to 50 fields that you define and displays up to 100 events.

windowcomp stage

When the stddev_sample statistical aggregate function is used with a windowcomp stage, the function returns a single sample (unbiased) standard deviation value of a field for each row in the group of rows, for all records that contain matching values for the fields identified using a combination of the by clause, sort, and between window frame clause. The results are provided in a new column in the results table.

Examples

comp stage example

Calculate a maximum of 100 metrics_source records, where the _broker_device_ip is 172.16.1.25, and include a single sample (unbiased) standard deviation value of the total_size_bytes field for a group of rows.

dataset = metrics_source 
| filter _broker_device_ip = "172.16.1.25" 
| comp stddev_sample(total_size_bytes)
| limit 100

windowcomp stage example

Return a maximum of 100 metrics_source records and include a single sample (unbiased) standard deviation value of the total_size_rate field for each row in the group of rows, for all records that contain matching values in the _broker_device_id field. The results are provided in the stddev_sample column.

dataset = metrics_source
| limit 100
| windowcomp stddev_sample(total_size_rate) by _broker_device_id as `stddev_sample`