---
title: count() function
description: >
  `count()` returns the number of records in each input table.
menu:
  flux_v0_ref:
    name: count
    parent: universe
    identifier: universe/count
weight: 101
flux/v0/tags: [transformations, aggregates]
introduced: 0.7.0
---

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

The function counts both null and non-null records.

#### Empty tables
`count()` returns `0` for empty tables.
To keep empty tables in your data, set the following parameters for the
following functions:

| Function            | Parameter           |
| :------------------ | :------------------ |
| `filter()`          | `onEmpty: "keep"`   |
| `window()`          | `createEmpty: true` |
| `aggregateWindow()` | `createEmpty: true` |

##### Function type signature

```js
(<-tables: stream[A], ?column: string) => stream[B] where A: Record, B: Record
```

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

### column

Column to count values in and store the total count.



### tables

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




## Examples

- [Count the number of records in each input table](#count-the-number-of-records-in-each-input-table)
- [Count the number of records with a specific value](#count-the-number-of-records-with-a-specific-value)

### Count the number of records in each input table

```js
import "sampledata"

sampledata.string()
    |> count()

```


### Count the number of records with a specific value

1. Use `filter()` to filter data by the specific value you want to count.
2. Use `count()` to count the number of rows in the table.

```js
import "sampledata"

data =
    sampledata.int()
        |> filter(fn: (r) => r._value > 10)

data
    |> count()

```

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#### Input data

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:30Z | 17      | t1   |
| 2021-01-01T00:00:40Z | 15      | t1   |

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | 19      | t2   |
| 2021-01-01T00:00:30Z | 19      | t2   |
| 2021-01-01T00:00:40Z | 13      | t2   |


#### Output data

| *tag | _value  |
| ---- | ------- |
| t1   | 2       |

| *tag | _value  |
| ---- | ------- |
| t2   | 3       |

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