---
title: tickscript.join() function
description: >
  `tickscript.join()` merges two input streams into a single output stream
  based on specified columns with equal values and appends a new measurement name.
menu:
  flux_v0_ref:
    name: tickscript.join
    parent: contrib/bonitoo-io/tickscript
    identifier: contrib/bonitoo-io/tickscript/join
weight: 301
flux/v0/tags: [transformations]
---

<!------------------------------------------------------------------------------

IMPORTANT: This page was generated from comments in the Flux source code. Any
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To make updates to this documentation, update the function comments above the
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------------------------------------------------------------------------------->

`tickscript.join()` merges two input streams into a single output stream
based on specified columns with equal values and appends a new measurement name.

This function is comparable to [Kapacitor JoinNode](/kapacitor/latest/nodes/join_node/).

##### Function type signature

```js
(measurement: A, tables: B, ?on: [string]) => stream[{C with _measurement: A}] where B: Record, C: Record
```

{{% caption %}}
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
{{% /caption %}}

## Parameters

### tables
({{< req >}})
Map of two streams to join.



### on

List of columns to join on. Default is `["_time"]`.



### measurement
({{< req >}})
Measurement name to use in results.




## Examples

### Join two streams of data

```js
import "array"
import "contrib/bonitoo-io/tickscript"

metrics =
    array.from(
        rows: [
            {_time: 2021-01-01T00:00:00Z, host: "host1", _value: 1.2},
            {_time: 2021-01-01T01:00:00Z, host: "host1", _value: 0.8},
            {_time: 2021-01-01T02:00:00Z, host: "host1", _value: 3.2},
            {_time: 2021-01-01T00:00:00Z, host: "host2", _value: 8.4},
            {_time: 2021-01-01T01:00:00Z, host: "host2", _value: 7.3},
            {_time: 2021-01-01T02:00:00Z, host: "host2", _value: 7.9},
        ],
    )
        |> group(columns: ["host"])

states =
    array.from(
        rows: [
            {_time: 2021-01-01T00:00:00Z, host: "host1", _value: "dead"},
            {_time: 2021-01-01T01:00:00Z, host: "host1", _value: "dead"},
            {_time: 2021-01-01T02:00:00Z, host: "host1", _value: "alive"},
            {_time: 2021-01-01T00:00:00Z, host: "host2", _value: "alive"},
            {_time: 2021-01-01T01:00:00Z, host: "host2", _value: "alive"},
            {_time: 2021-01-01T02:00:00Z, host: "host2", _value: "alive"},
        ],
    )
        |> group(columns: ["host"])

tickscript.join(
    tables: {metric: metrics, state: states},
    on: ["_time", "host"],
    measurement: "example-m",
)

```

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{{% expand "View example output" %}}

#### Output data

| *_measurement | _time                | _value_metric  | _value_state  | *host |
| ------------- | -------------------- | -------------- | ------------- | ----- |
| example-m     | 2021-01-01T00:00:00Z | 1.2            | dead          | host1 |
| example-m     | 2021-01-01T01:00:00Z | 0.8            | dead          | host1 |
| example-m     | 2021-01-01T02:00:00Z | 3.2            | alive         | host1 |

| *_measurement | _time                | _value_metric  | _value_state  | *host |
| ------------- | -------------------- | -------------- | ------------- | ----- |
| example-m     | 2021-01-01T00:00:00Z | 8.4            | alive         | host2 |
| example-m     | 2021-01-01T01:00:00Z | 7.3            | alive         | host2 |
| example-m     | 2021-01-01T02:00:00Z | 7.9            | alive         | host2 |

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{{< /expand-wrapper >}}