---
title: monitor.deadman() function
description: monitor.deadman() detects when a group stops reporting data. It takes a stream of tables and reports if groups have been observed since time t.
url: https://docs.influxdata.com/flux/v0/stdlib/influxdata/influxdb/monitor/deadman/
estimated_tokens: 2636
product: Flux
version: v0
---

# monitor.deadman() function

-   Flux 0.39.0+
-   View InfluxDB support

`monitor.deadman()` detects when a group stops reporting data. It takes a stream of tables and reports if groups have been observed since time `t`.

`monitor.deadman()` retains the most recent row from each input table and adds a `dead` column. If a record appears after time `t`, `monitor.deadman()` sets `dead` to `false`. Otherwise, `dead` is set to `true`.

##### Function type signature

```js
(<-tables: stream[{B with _time: C}], t: A) => stream[{B with dead: bool, _time: C}] where A: Comparable, C: Comparable
```

For more information, see [Function type signatures](/flux/v0/function-type-signatures/).

## Parameters

### t

(Required) Time threshold for the deadman check.

### tables

Input data. Default is piped-forward data (`<-`).

## Examples

-   [Detect if a host hasn’t reported since a specific time](#detect-if-a-host-hasnt-reported-since-a-specific-time)
-   [Detect if a host hasn’t reported since a relative time](#detect-if-a-host-hasnt-reported-since-a-relative-time)

### Detect if a host hasn’t reported since a specific time

```js
import "array"
import "influxdata/influxdb/monitor"

data =
    array.from(
        rows: [
            {_time: 2021-01-01T00:00:00Z, host: "a", _value: 1.2},
            {_time: 2021-01-01T00:01:00Z, host: "a", _value: 1.3},
            {_time: 2021-01-01T00:02:00Z, host: "a", _value: 1.4},
            {_time: 2021-01-01T00:03:00Z, host: "a", _value: 1.3},
        ],
    )
        |> group(columns: ["host"])

data
    |> monitor.deadman(t: 2021-01-01T00:05:00Z)
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | *host | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | a | 1.2 |
| 2021-01-01T00:01:00Z | a | 1.3 |
| 2021-01-01T00:02:00Z | a | 1.4 |
| 2021-01-01T00:03:00Z | a | 1.3 |

#### Output data

| _time | _value | dead | *host |
| --- | --- | --- | --- |
| 2021-01-01T00:03:00Z | 1.3 | true | a |

### Detect if a host hasn’t reported since a relative time

Use `date.add()` to return a time value relative to a specified time.

```js
import "influxdata/influxdb/monitor"
import "date"

from(bucket: "example-bucket")
    |> range(start: -10m)
    |> filter(fn: (r) => r._measurement == "example-measurement")
    |> monitor.deadman(t: date.add(d: -5m, to: now()))
```

[transformations](/flux/v0/tags/transformations/)