---
title: schema.measurementFieldKeys() function
description: >
  `schema.measurementFieldKeys()` returns a list of fields in a measurement.
menu:
  flux_v0_ref:
    name: schema.measurementFieldKeys
    parent: influxdata/influxdb/schema
    identifier: influxdata/influxdb/schema/measurementFieldKeys
weight: 301
flux/v0/tags: [metadata]
---

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`schema.measurementFieldKeys()` returns a list of fields in a measurement.

Results include a single table with a single column, `_value`.

##### Function type signature

```js
(bucket: string, measurement: A, ?start: B, ?stop: C) => stream[D] where A: Equatable, D: Record
```

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

## Parameters

### bucket
({{< req >}})
Bucket to retrieve field keys from.



### measurement
({{< req >}})
Measurement to list field keys from.



### start

Oldest time to include in results. Default is `-30d`.



### stop

Newest time include in results.
The stop time is exclusive, meaning values with a time equal to stop time are excluded from the results.
Default is `now()`.

Relative start times are defined using negative durations.
Negative durations are relative to `now()`.
Absolute start times are defined using time values.


## Examples

### Query field keys from an InfluxDB measurement

```js
import "influxdata/influxdb/schema"

schema.measurementFieldKeys(bucket: "example-bucket", measurement: "example-measurement")

```