docs-v2/content/flux/v0/stdlib/experimental/count.md

title	description	menu	weight	flux/v0/tags	introduced
experimental.count() function	`experimental.count()` returns the number of records in each input table.	flux_v0_ref name parent identifier experimental.count experimental experimental/count	101	transformations aggregates	0.107.0

experimental.count() returns the number of records in each input table.

The count is returned in the _value column and counts both null and non-null records.

Counts on empty tables

experimental.count() returns 0 for empty tables. To keep empty tables in your data, set the following parameters when using the following functions:

filter(onEmpty: "keep")
window(createEmpty: true)
aggregateWindow(createEmpty: true)

Function type signature

(<-tables: stream[{A with _value: B}]) => stream[{A with _value: int}]

{{% caption %}} For more information, see Function type signatures. {{% /caption %}}

Parameters

tables

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

Examples

Count the number of rows in a table

import "experimental"
import "sampledata"

sampledata.int()
    |> experimental.count()

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Input data

_time	_value	*tag
2021-01-01T00:00:00Z	-2	t1
2021-01-01T00:00:10Z	10	t1
2021-01-01T00:00:20Z	7	t1
2021-01-01T00:00:30Z	17	t1
2021-01-01T00:00:40Z	15	t1
2021-01-01T00:00:50Z	4	t1

_time	_value	*tag
2021-01-01T00:00:00Z	19	t2
2021-01-01T00:00:10Z	4	t2
2021-01-01T00:00:20Z	-3	t2
2021-01-01T00:00:30Z	19	t2
2021-01-01T00:00:40Z	13	t2
2021-01-01T00:00:50Z	1	t2

Output data

*tag	_value
t1	6

*tag	_value
t2	6

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