159 lines
4.5 KiB
Markdown
159 lines
4.5 KiB
Markdown
---
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title: experimental.join() function
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description: >
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`experimental.join()` joins two streams of tables on the **group key and `_time` column**.
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menu:
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flux_v0_ref:
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name: experimental.join
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parent: experimental
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identifier: experimental/join
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weight: 101
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flux/v0/tags: [transformations]
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introduced: 0.65.0
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deprecated: 0.172.0
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---
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<!------------------------------------------------------------------------------
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IMPORTANT: This page was generated from comments in the Flux source code. Any
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edits made directly to this page will be overwritten the next time the
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documentation is generated.
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To make updates to this documentation, update the function comments above the
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function definition in the Flux source code:
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https://github.com/influxdata/flux/blob/master/stdlib/experimental/experimental.flux#L399-L403
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Contributing to Flux: https://github.com/influxdata/flux#contributing
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Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
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------------------------------------------------------------------------------->
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`experimental.join()` joins two streams of tables on the **group key and `_time` column**.
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{{% warn %}}
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#### Deprecated
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`experimental.join()` is deprecated in favor of [`join.time()`](/flux/v0/stdlib/join/time/).
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The [`join` package](/flux/v0/stdlib/join/) provides support
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for multiple join methods.
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{{% /warn %}}
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Use the `fn` parameter to map new output tables using values from input tables.
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**Note**: To join streams of tables with different fields or measurements,
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use `group()` or `drop()` to remove `_field` and `_measurement` from the
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group key before joining.
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##### Function type signature
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```js
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(fn: (left: A, right: B) => C, left: stream[A], right: stream[B]) => stream[C] where A: Record, B: Record, C: Record
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```
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{{% caption %}}
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For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
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{{% /caption %}}
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## Parameters
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### left
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({{< req >}})
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First of two streams of tables to join.
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### right
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({{< req >}})
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Second of two streams of tables to join.
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### fn
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({{< req >}})
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Function with left and right arguments that maps a new output record
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using values from the `left` and `right` input records.
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The return value must be a record.
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## Examples
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- [Join two streams of tables](#join-two-streams-of-tables)
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- [Join two streams of tables with different fields and measurements](#join-two-streams-of-tables-with-different-fields-and-measurements)
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### Join two streams of tables
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```js
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import "array"
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import "experimental"
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left =
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array.from(
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rows: [
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{_time: 2021-01-01T00:00:00Z, _field: "temp", _value: 80.1},
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{_time: 2021-01-01T01:00:00Z, _field: "temp", _value: 80.6},
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{_time: 2021-01-01T02:00:00Z, _field: "temp", _value: 79.9},
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{_time: 2021-01-01T03:00:00Z, _field: "temp", _value: 80.1},
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],
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)
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right =
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array.from(
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rows: [
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{_time: 2021-01-01T00:00:00Z, _field: "temp", _value: 75.1},
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{_time: 2021-01-01T01:00:00Z, _field: "temp", _value: 72.6},
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{_time: 2021-01-01T02:00:00Z, _field: "temp", _value: 70.9},
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{_time: 2021-01-01T03:00:00Z, _field: "temp", _value: 71.1},
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],
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)
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experimental.join(
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left: left,
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right: right,
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fn: (left, right) =>
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({left with lv: left._value, rv: right._value, diff: left._value - right._value}),
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)
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```
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{{< expand-wrapper >}}
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{{% expand "View example output" %}}
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#### Output data
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| _field | _time | _value | diff | lv | rv |
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| ------- | -------------------- | ------- | ----- | ---- | ---- |
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| temp | 2021-01-01T00:00:00Z | 80.1 | 5 | 80.1 | 75.1 |
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| temp | 2021-01-01T01:00:00Z | 80.6 | 8 | 80.6 | 72.6 |
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| temp | 2021-01-01T02:00:00Z | 79.9 | 9 | 79.9 | 70.9 |
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| temp | 2021-01-01T03:00:00Z | 80.1 | 9 | 80.1 | 71.1 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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### Join two streams of tables with different fields and measurements
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```js
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import "experimental"
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s1 =
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from(bucket: "example-bucket")
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|> range(start: -1h)
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|> filter(fn: (r) => r._measurement == "foo" and r._field == "bar")
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|> group(columns: ["_time", "_measurement", "_field", "_value"], mode: "except")
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s2 =
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from(bucket: "example-bucket")
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|> range(start: -1h)
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|> filter(fn: (r) => r._measurement == "baz" and r._field == "quz")
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|> group(columns: ["_time", "_measurement", "_field", "_value"], mode: "except")
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experimental.join(
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left: s1,
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right: s2,
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fn: (left, right) => ({left with bar_value: left._value, quz_value: right._value}),
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)
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```
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