stateDuration() function

The stateDuration() function computes the duration of a given state. The state is defined via the function fn. For each consecutive point for that evaluates as true, the state duration will be incremented by the duration between points. When a point evaluates as false, the state duration is reset. The state duration is added as an additional column to each record.

Function type: Transformation
Output data type: Duration

As the first point in the given state has no previous point, its state duration will be 0.

stateDuration(fn: (r) => r._measurement == "state", lable: "stateDuration", unit: 1s)

If the expression generates an error during evaluation, the point is discarded, and does not affect the state duration.

Parameters

fn

A single argument function that evaluates true or false to identify the state of the record. Records are passed to the function. Those that evaluate to true increment the state duration. Those that evaluate to false reset the state duration.

Data type: Function

label

The name of the column added to each record that contains the state duration.

Data type: String

unit

The unit of time in which the state duration is incremented. For example: 1s, 1m, 1h, etc.

Data type: Duration

Examples

from("monitor/autogen")
  |> range(start: -1h)
  |> filter(fn: (r) => r._measurement == "server_state")
  |> stateDuration()

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