143 lines
4.0 KiB
Markdown
143 lines
4.0 KiB
Markdown
---
|
|
title: join.full() function
|
|
description: >
|
|
`join.full()` performs a full outer join on two table streams.
|
|
menu:
|
|
flux_v0_ref:
|
|
name: join.full
|
|
parent: join
|
|
identifier: join/full
|
|
weight: 101
|
|
flux/v0/tags: [transformations]
|
|
introduced: 0.172.0
|
|
---
|
|
|
|
<!------------------------------------------------------------------------------
|
|
|
|
IMPORTANT: This page was generated from comments in the Flux source code. Any
|
|
edits made directly to this page will be overwritten the next time the
|
|
documentation is generated.
|
|
|
|
To make updates to this documentation, update the function comments above the
|
|
function definition in the Flux source code:
|
|
|
|
https://github.com/influxdata/flux/blob/master/stdlib/join/join.flux#L392-L399
|
|
|
|
Contributing to Flux: https://github.com/influxdata/flux#contributing
|
|
Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
|
|
|
|
------------------------------------------------------------------------------->
|
|
|
|
`join.full()` performs a full outer join on two table streams.
|
|
|
|
The function calls `join.tables()` with the `method` parameter set to `"full"`.
|
|
|
|
##### Function type signature
|
|
|
|
```js
|
|
(<-left: stream[A], as: (l: A, r: B) => C, on: (l: A, r: B) => bool, right: stream[B]) => stream[C] where A: Record, B: Record, C: Record
|
|
```
|
|
|
|
{{% caption %}}
|
|
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
|
|
{{% /caption %}}
|
|
|
|
## Parameters
|
|
|
|
### left
|
|
|
|
Left input stream. Default is piped-forward data (<-).
|
|
|
|
|
|
|
|
### right
|
|
({{< req >}})
|
|
Right input stream.
|
|
|
|
|
|
|
|
### on
|
|
({{< req >}})
|
|
Function that takes a left and right record (`l`, and `r` respectively), and returns a boolean.
|
|
|
|
The body of the function must be a single boolean expression, consisting of one
|
|
or more equality comparisons between a property of `l` and a property of `r`,
|
|
each chained together by the `and` operator.
|
|
|
|
### as
|
|
({{< req >}})
|
|
Function that takes a left and a right record (`l` and `r` respectively), and returns a record.
|
|
The returned record is included in the final output.
|
|
|
|
|
|
|
|
|
|
## Examples
|
|
|
|
### Perform a full outer join
|
|
|
|
In a full outer join, either `l` or `r` could be a default record, but they will
|
|
never both be a default record at the same time.
|
|
|
|
To get non-null values for the output record, check both `l` and `r` to see which contains
|
|
the desired values.
|
|
|
|
The example below defines a function for the `as` parameter that appropriately handles
|
|
the uncertainty of a full outer join.
|
|
|
|
`v_left` and `v_right` still use values from `l` and `r` directly, because we expect
|
|
them to sometimes be null in the output table.
|
|
|
|
For more information about the behavior of outer joins, see the [Outer joins](/flux/v0/stdlib/join/#outer-joins)
|
|
section in the `join` package documentation.
|
|
|
|
```js
|
|
import "array"
|
|
import "join"
|
|
|
|
left =
|
|
array.from(
|
|
rows: [
|
|
{_time: 2022-01-01T00:00:00Z, _value: 1, label: "a"},
|
|
{_time: 2022-01-01T00:00:00Z, _value: 2, label: "b"},
|
|
{_time: 2022-01-01T00:00:00Z, _value: 3, label: "d"},
|
|
],
|
|
)
|
|
right =
|
|
array.from(
|
|
rows: [
|
|
{_time: 2022-01-01T00:00:00Z, _value: 0.4, id: "a"},
|
|
{_time: 2022-01-01T00:00:00Z, _value: 0.5, id: "c"},
|
|
{_time: 2022-01-01T00:00:00Z, _value: 0.6, id: "d"},
|
|
],
|
|
)
|
|
|
|
join.full(
|
|
left: left,
|
|
right: right,
|
|
on: (l, r) => l.label == r.id and l._time == r._time,
|
|
as: (l, r) => {
|
|
time = if exists l._time then l._time else r._time
|
|
label = if exists l.label then l.label else r.id
|
|
|
|
return {_time: time, label: label, v_left: l._value, v_right: r._value}
|
|
},
|
|
)
|
|
|
|
```
|
|
|
|
{{< expand-wrapper >}}
|
|
{{% expand "View example output" %}}
|
|
|
|
#### Output data
|
|
|
|
| _time | label | v_left | v_right |
|
|
| -------------------- | ------ | ------- | -------- |
|
|
| 2022-01-01T00:00:00Z | a | 1 | 0.4 |
|
|
| 2022-01-01T00:00:00Z | b | 2 | |
|
|
| 2022-01-01T00:00:00Z | c | | 0.5 |
|
|
| 2022-01-01T00:00:00Z | d | 3 | 0.6 |
|
|
|
|
{{% /expand %}}
|
|
{{< /expand-wrapper >}}
|