119 lines
3.1 KiB
Markdown
119 lines
3.1 KiB
Markdown
---
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title: tail() function
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description: The `tail()` function limits each output table to the last `n` records.
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aliases:
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- /influxdb/v2.0/reference/flux/functions/built-in/transformations/tail/
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- /influxdb/v2.0/reference/flux/stdlib/built-in/transformations/tail/
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- /influxdb/cloud/reference/flux/stdlib/built-in/transformations/tail/
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menu:
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flux_0_x_ref:
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name: tail
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parent: universe
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weight: 102
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flux/v0.x/tags: [transformations]
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related:
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- /flux/v0.x/stdlib/universe/limit/
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introduced: 0.39.0
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---
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The `tail()` function limits each output table to the last [`n`](#n) records.
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The function produces one output table for each input table.
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Each output table contains the last `n` records before the [`offset`](#offset).
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If the input table has less than `offset + n` records, `tail()` outputs all records before the `offset`.
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```js
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tail(n: 10, offset: 0)
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```
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## Parameters
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### n {data-type="int"}
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({{< req >}})
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The maximum number of records to output.
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### offset {data-type="int"}
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The number of records to skip at the end of a table table before limiting to `n`.
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Default is `0`.
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### tables {data-type="stream of tables"}
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Input data.
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Default is piped-forward data ([`<-`](/flux/v0.x/spec/expressions/#pipe-expressions)).
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## Examples
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{{% flux/sample-example-intro %}}
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- [Output the last three rows in each input table](#output-the-last-three-rows-in-each-input-table)
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- [Output the last three rows before the last row in each input table](#output-the-last-three-rows-before-the-last-row-in-each-input-table)
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#### Output the last three rows in each input table
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```js
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import "sampledata"
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sampledata.int()
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|> tail(n: 3)
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```
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{{< expand-wrapper >}}
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{{% expand "View input and output" %}}
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{{< flex >}}
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{{% flex-content %}}
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##### Input data
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{{% flux/sample "int" %}}
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{{% /flex-content %}}
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{{% flex-content %}}
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##### Output data
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:30Z | t1 | 17 |
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| 2021-01-01T00:00:40Z | t1 | 15 |
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| 2021-01-01T00:00:50Z | t1 | 4 |
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:30Z | t2 | 19 |
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| 2021-01-01T00:00:40Z | t2 | 13 |
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| 2021-01-01T00:00:50Z | t2 | 1 |
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{{% /flex-content %}}
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{{< /flex >}}
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{{% /expand %}}
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{{< /expand-wrapper >}}
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#### Output the last three rows before the last row in each input table
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```js
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import "sampledata"
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sampledata.int()
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|> tail(n: 3, offset: 1)
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```
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{{< expand-wrapper >}}
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{{% expand "View input and output" %}}
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{{< flex >}}
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{{% flex-content %}}
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##### Input data
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{{% flux/sample "int" %}}
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{{% /flex-content %}}
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{{% flex-content %}}
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##### Output data
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:20Z | t1 | 7 |
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| 2021-01-01T00:00:30Z | t1 | 17 |
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| 2021-01-01T00:00:40Z | t1 | 15 |
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| _time | tag | _value |
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| :------------------- | :-- | -----: |
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| 2021-01-01T00:00:20Z | t2 | -3 |
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| 2021-01-01T00:00:30Z | t2 | 19 |
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| 2021-01-01T00:00:40Z | t2 | 13 |
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{{% /flex-content %}}
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{{< /flex >}}
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{{% /expand %}}
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{{< /expand-wrapper >}}
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