---
title: join package
description: The join package provides functions that join two table streams together.
url: https://docs.influxdata.com/flux/v0/stdlib/join/
estimated_tokens: 702
product: Flux
version: v0
---

# join package

-   Flux 0.172.0+
-   View InfluxDB support

The `join` package provides functions that join two table streams together. Import the `join` package:

```js
import "join"
```

## Outer joins

The join transformation supports left, right, and full outer joins.

-   **Left outer joins** generate at least one output row for each record in the left input stream. If a record in the left input stream does not have a match in the right input stream, `r` is substituted with a default record in the `as` function.
-   **Right outer joins** generate at least one output row for each record in the right input stream. If a record in the right input stream does not have a match in the left input stream, `l` is substituted with a default record in the `as` function.
-   **Full outer joins** generate at least one output row for each record in both input streams. If a record in either input stream doesn’t have a match in the other input stream, one of the arguments to the `as` function is substituted with a default record (either `l` or `r`, depending on which one is missing the matching record)

A default record has the same columns as the records in the corresponding input table, but only group key columns are populated with a value. All other columns are null.

## Inner joins

Inner joins drop any records that don’t have a match in the other input stream. There is no need to account for default or unmatched records when performing an inner join.

## Functions

-   [join.full()](/flux/v0/stdlib/join/full/)
-   [join.inner()](/flux/v0/stdlib/join/inner/)
-   [join.left()](/flux/v0/stdlib/join/left/)
-   [join.right()](/flux/v0/stdlib/join/right/)
-   [join.tables()](/flux/v0/stdlib/join/tables/)
-   [join.time()](/flux/v0/stdlib/join/time/)

#### Related

-   [Join data](/flux/v0/join-data/)
-   [Troubleshoot join operations](/flux/v0/join-data/troubleshoot-joins/)

[transformations](/flux/v0/tags/transformations/)