---
title: keyValues() function
description: >
  `keyValues()` returns a stream of tables with each input tables' group key and
  two columns, _key and _value, that correspond to unique column label and value
  pairs for each input table.
menu:
  flux_v0_ref:
    name: keyValues
    parent: universe
    identifier: universe/keyValues
weight: 101
flux/v0/tags: [transformations]
introduced: 0.13.0
---

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------------------------------------------------------------------------------->

`keyValues()` returns a stream of tables with each input tables' group key and
two columns, _key and _value, that correspond to unique column label and value
pairs for each input table.



##### Function type signature

```js
(<-tables: stream[A], ?keyColumns: [string]) => stream[{B with _value: C, _key: string}] where A: Record, B: Record
```

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

## Parameters

### keyColumns

List of columns from which values are extracted.

All columns must be of the same type.
Each input table must have all of the columns in the `keyColumns` parameter.

### tables

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




## Examples

### Get key values from explicitly defined columns

```js
data
    |> keyValues(keyColumns: ["sensorID", "_field"])

```

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{{% expand "View example input and output" %}}

#### Input data

| *_field | *_measurement | *sensorID | _time                | _value  |
| ------- | ------------- | --------- | -------------------- | ------- |
| co      | airSensors    | TLM0100   | 2021-09-08T14:21:57Z | 0.31    |
| co      | airSensors    | TLM0100   | 2021-09-08T14:22:07Z | 0.295   |
| co      | airSensors    | TLM0100   | 2021-09-08T14:22:17Z | 0.314   |
| co      | airSensors    | TLM0100   | 2021-09-08T14:22:27Z | 0.313   |

| *_field  | *_measurement | *sensorID | _time                | _value  |
| -------- | ------------- | --------- | -------------------- | ------- |
| humidity | airSensors    | TLM0100   | 2021-09-08T14:21:57Z | 36.03   |
| humidity | airSensors    | TLM0100   | 2021-09-08T14:22:07Z | 36.07   |
| humidity | airSensors    | TLM0100   | 2021-09-08T14:22:17Z | 36.1    |
| humidity | airSensors    | TLM0100   | 2021-09-08T14:22:27Z | 36.12   |

| *_field     | *_measurement | *sensorID | _time                | _value  |
| ----------- | ------------- | --------- | -------------------- | ------- |
| temperature | airSensors    | TLM0100   | 2021-09-08T14:21:57Z | 70.84   |
| temperature | airSensors    | TLM0100   | 2021-09-08T14:22:07Z | 70.86   |
| temperature | airSensors    | TLM0100   | 2021-09-08T14:22:17Z | 70.89   |
| temperature | airSensors    | TLM0100   | 2021-09-08T14:22:27Z | 70.85   |


#### Output data

| *_field | *_measurement | *sensorID | _key     | _value  |
| ------- | ------------- | --------- | -------- | ------- |
| co      | airSensors    | TLM0100   | sensorID | TLM0100 |
| co      | airSensors    | TLM0100   | _field   | co      |

| *_field  | *_measurement | *sensorID | _key     | _value   |
| -------- | ------------- | --------- | -------- | -------- |
| humidity | airSensors    | TLM0100   | sensorID | TLM0100  |
| humidity | airSensors    | TLM0100   | _field   | humidity |

| *_field     | *_measurement | *sensorID | _key     | _value      |
| ----------- | ------------- | --------- | -------- | ----------- |
| temperature | airSensors    | TLM0100   | sensorID | TLM0100     |
| temperature | airSensors    | TLM0100   | _field   | temperature |

{{% /expand %}}
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