161 lines
4.3 KiB
Markdown
161 lines
4.3 KiB
Markdown
---
|
|
title: join() function
|
|
description: >
|
|
`join()` merges two streams of tables into a single output stream based on columns with equal values.
|
|
Null values are not considered equal when comparing column values.
|
|
The resulting schema is the union of the input schemas.
|
|
The resulting group key is the union of the input group keys.
|
|
menu:
|
|
flux_v0_ref:
|
|
name: join
|
|
parent: universe
|
|
identifier: universe/join
|
|
weight: 101
|
|
flux/v0/tags: [transformations]
|
|
introduced: 0.7.0
|
|
deprecated: 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/universe/universe.flux#L1184-L1184
|
|
|
|
Contributing to Flux: https://github.com/influxdata/flux#contributing
|
|
Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
|
|
|
|
------------------------------------------------------------------------------->
|
|
|
|
`join()` merges two streams of tables into a single output stream based on columns with equal values.
|
|
Null values are not considered equal when comparing column values.
|
|
The resulting schema is the union of the input schemas.
|
|
The resulting group key is the union of the input group keys.
|
|
|
|
{{% warn %}}
|
|
#### Deprecated
|
|
`join()` is deprecated in favor of [`join.inner()`](/flux/v0/stdlib/join/inner/).
|
|
The [`join` package](/flux/v0/stdlib/join/) provides support
|
|
for multiple join methods.
|
|
{{% /warn %}}
|
|
|
|
#### Output data
|
|
The schema and group keys of the joined output output data is the union of
|
|
the input schemas and group keys.
|
|
Columns that exist in both input streams that are not part specified as
|
|
columns to join on are renamed using the pattern `<column>_<table>` to
|
|
prevent ambiguity in joined tables.
|
|
|
|
### Join vs union
|
|
`join()` creates new rows based on common values in one or more specified columns.
|
|
Output rows also contain the differing values from each of the joined streams.
|
|
`union()` does not modify data in rows, but unions separate streams of tables
|
|
into a single stream of tables and groups rows of data based on existing group keys.
|
|
|
|
##### Function type signature
|
|
|
|
```js
|
|
(<-tables: A, ?method: string, ?on: [string]) => stream[B] where A: Record, B: Record
|
|
```
|
|
|
|
{{% caption %}}
|
|
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
|
|
{{% /caption %}}
|
|
|
|
## Parameters
|
|
|
|
### tables
|
|
|
|
Record containing two input streams to join.
|
|
|
|
|
|
|
|
### on
|
|
|
|
List of columns to join on.
|
|
|
|
|
|
|
|
### method
|
|
|
|
Join method. Default is `inner`.
|
|
|
|
**Supported methods**:
|
|
- inner
|
|
|
|
|
|
## Examples
|
|
|
|
- [Join two streams of tables](#join-two-streams-of-tables)
|
|
- [Join data from separate data sources](#join-data-from-separate-data-sources)
|
|
|
|
### Join two streams of tables
|
|
|
|
```js
|
|
import "generate"
|
|
|
|
t1 =
|
|
generate.from(
|
|
count: 4,
|
|
fn: (n) => n + 1,
|
|
start: 2021-01-01T00:00:00Z,
|
|
stop: 2021-01-05T00:00:00Z,
|
|
)
|
|
|> set(key: "tag", value: "foo")
|
|
|
|
t2 =
|
|
generate.from(
|
|
count: 4,
|
|
fn: (n) => n * (-1),
|
|
start: 2021-01-01T00:00:00Z,
|
|
stop: 2021-01-05T00:00:00Z,
|
|
)
|
|
|> set(key: "tag", value: "foo")
|
|
|
|
join(tables: {t1: t1, t2: t2}, on: ["_time", "tag"])
|
|
|
|
```
|
|
|
|
{{< expand-wrapper >}}
|
|
{{% expand "View example output" %}}
|
|
|
|
#### Output data
|
|
|
|
| _time | _value_t1 | _value_t2 | tag |
|
|
| -------------------- | ---------- | ---------- | ---- |
|
|
| 2021-01-01T00:00:00Z | 1 | 0 | foo |
|
|
| 2021-01-02T00:00:00Z | 2 | -1 | foo |
|
|
| 2021-01-03T00:00:00Z | 3 | -2 | foo |
|
|
| 2021-01-04T00:00:00Z | 4 | -3 | foo |
|
|
|
|
{{% /expand %}}
|
|
{{< /expand-wrapper >}}
|
|
|
|
### Join data from separate data sources
|
|
|
|
```js
|
|
import "sql"
|
|
|
|
sqlData =
|
|
sql.from(
|
|
driverName: "postgres",
|
|
dataSourceName: "postgresql://username:password@localhost:5432",
|
|
query: "SELECT * FROM example_table",
|
|
)
|
|
|
|
tsData =
|
|
from(bucket: "example-bucket")
|
|
|> range(start: -1h)
|
|
|> filter(fn: (r) => r._measurement == "example-measurement")
|
|
|> filter(fn: (r) => exists r.sensorID)
|
|
|
|
join(tables: {sql: sqlData, ts: tsData}, on: ["_time", "sensorID"])
|
|
|
|
```
|
|
|