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ported kapacitor 1.4
2020-07-30 16:38:32 +00:00
---
title: JoinNode (Kapacitor TICKscript node)
description: JoinNode joins the data from any number of nodes. As each data point is received from a parent node it is paired with the next data points from the other parent nodes with a matching timestamp.
note: Auto generated by tickdoc
menu:
kapacitor_1_4:
name: JoinNode
identifier: join_node
weight: 170
parent: TICKscript nodes
---
### Constructor
| Chaining Method | Description |
|:---------|:---------|
| **[join](#descr) ( `others` `...Node`)** | Join this node with other nodes. The data is joined on timestamp. |
### Property Methods
| Setters | Description |
|:---|:---|
| **[as](#as) ( `names` `...string`)** | Prefix names for all fields from the respective nodes. Each field from the parent nodes will be prefixed with the provided name and a '.'. See the example below. |
| **[delimiter](#delimiter) ( `value` `string`)** | The delimiter for the field name prefixes. Can be the empty string. |
| **[fill](#fill) ( `value` `interface{}`)** | Fill the data. The fill option implies the type of join: inner or full outer Options are: |
| **[on](#on) ( `dims` `...string`)** | Join on a subset of the group by dimensions. This is a special case where you want a single point from one parent to join with multiple points from a different parent. |
| **[streamName](#streamname) ( `value` `string`)** | The name of this new joined data stream. If empty the name of the left parent is used. |
| **[tolerance](#tolerance) ( `value` `time.Duration`)** | The maximum duration of time that two incoming points can be apart and still be considered to be equal in time. The joined data point's time will be rounded to the nearest multiple of the tolerance duration. |
### Chaining Methods
[Alert](/kapacitor/v1.4/nodes/join_node/#alert), [Barrier](/kapacitor/v1.4/nodes/join_node/#barrier), [Bottom](/kapacitor/v1.4/nodes/join_node/#bottom), [Combine](/kapacitor/v1.4/nodes/join_node/#combine), [Count](/kapacitor/v1.4/nodes/join_node/#count), [CumulativeSum](/kapacitor/v1.4/nodes/join_node/#cumulativesum), [Deadman](/kapacitor/v1.4/nodes/join_node/#deadman), [Default](/kapacitor/v1.4/nodes/join_node/#default), [Delete](/kapacitor/v1.4/nodes/join_node/#delete), [Derivative](/kapacitor/v1.4/nodes/join_node/#derivative), [Difference](/kapacitor/v1.4/nodes/join_node/#difference), [Distinct](/kapacitor/v1.4/nodes/join_node/#distinct), [Ec2Autoscale](/kapacitor/v1.4/nodes/join_node/#ec2autoscale), [Elapsed](/kapacitor/v1.4/nodes/join_node/#elapsed), [Eval](/kapacitor/v1.4/nodes/join_node/#eval), [First](/kapacitor/v1.4/nodes/join_node/#first), [Flatten](/kapacitor/v1.4/nodes/join_node/#flatten), [GroupBy](/kapacitor/v1.4/nodes/join_node/#groupby), [HoltWinters](/kapacitor/v1.4/nodes/join_node/#holtwinters), [HoltWintersWithFit](/kapacitor/v1.4/nodes/join_node/#holtwinterswithfit), [HttpOut](/kapacitor/v1.4/nodes/join_node/#httpout), [HttpPost](/kapacitor/v1.4/nodes/join_node/#httppost), [InfluxDBOut](/kapacitor/v1.4/nodes/join_node/#influxdbout), [Join](/kapacitor/v1.4/nodes/join_node/#join), [K8sAutoscale](/kapacitor/v1.4/nodes/join_node/#k8sautoscale), [KapacitorLoopback](/kapacitor/v1.4/nodes/join_node/#kapacitorloopback), [Last](/kapacitor/v1.4/nodes/join_node/#last), [Log](/kapacitor/v1.4/nodes/join_node/#log), [Max](/kapacitor/v1.4/nodes/join_node/#max), [Mean](/kapacitor/v1.4/nodes/join_node/#mean), [Median](/kapacitor/v1.4/nodes/join_node/#median), [Min](/kapacitor/v1.4/nodes/join_node/#min), [Mode](/kapacitor/v1.4/nodes/join_node/#mode), [MovingAverage](/kapacitor/v1.4/nodes/join_node/#movingaverage), [Percentile](/kapacitor/v1.4/nodes/join_node/#percentile), [Sample](/kapacitor/v1.4/nodes/join_node/#sample), [Shift](/kapacitor/v1.4/nodes/join_node/#shift), [Sideload](/kapacitor/v1.4/nodes/join_node/#sideload), [Spread](/kapacitor/v1.4/nodes/join_node/#spread), [StateCount](/kapacitor/v1.4/nodes/join_node/#statecount), [StateDuration](/kapacitor/v1.4/nodes/join_node/#stateduration), [Stats](/kapacitor/v1.4/nodes/join_node/#stats), [Stddev](/kapacitor/v1.4/nodes/join_node/#stddev), [Sum](/kapacitor/v1.4/nodes/join_node/#sum), [SwarmAutoscale](/kapacitor/v1.4/nodes/join_node/#swarmautoscale), [Top](/kapacitor/v1.4/nodes/join_node/#top), [Union](/kapacitor/v1.4/nodes/join_node/#union), [Where](/kapacitor/v1.4/nodes/join_node/#where), [Window](/kapacitor/v1.4/nodes/join_node/#window)
<a id='descr'/><hr/><br/>
### Description
Joins the data from any number of nodes.
As each data point is received from a parent node it is paired
with the next data points from the other parent nodes with a
matching timestamp. Each parent node contributes at most one point
to each joined point. A tolerance can be supplied to join points
that do not have perfectly aligned timestamps.
Any points that fall within the tolerance are joined on the timestamp.
If multiple points fall within the same tolerance window than they are joined in the order
they arrive.
Aliases are used to prefix all fields from the respective nodes.
The join can be an inner or outer join, see the [JoinNode.Fill](/kapacitor/v1.4/nodes/join_node/#fill) property.
Example:
```javascript
var errors = stream
|from()
.measurement('errors')
var requests = stream
|from()
.measurement('requests')
// Join the errors and requests streams
errors
|join(requests)
// Provide prefix names for the fields of the data points.
.as('errors', 'requests')
// points that are within 1 second are considered the same time.
.tolerance(1s)
// fill missing values with 0, implies outer join.
.fill(0.0)
// name the resulting stream
.streamName('error_rate')
// Both the "value" fields from each parent have been prefixed
// with the respective names 'errors' and 'requests'.
|eval(lambda: "errors.value" / "requests.value")
.as('rate')
...
```
In the above example the `errors` and `requests` streams are joined
and then transformed to calculate a combined field.
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
Properties
----------
Property methods modify state on the calling node.
They do not add another node to the pipeline, and always return a reference to the calling node.
Property methods are marked using the `.` operator.
### As
Prefix names for all fields from the respective nodes.
Each field from the parent nodes will be prefixed with the provided name and a '.'.
See the example above.
The names cannot have a dot '.' character.
```javascript
join.as(names ...string)
```
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Delimiter
The delimiter for the field name prefixes.
Can be the empty string.
```javascript
join.delimiter(value string)
```
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Fill
Fill the data.
The fill option implies the type of join: inner or full outer
Options are:
- none - (default) skip rows where a point is missing, inner join.
- null - fill missing points with null, full outer join.
- Any numerical value - fill fields with given value, full outer join.
When using a numerical or null fill, the fields names are determined by copying
the field names from another point.
This doesn't work well when different sources have different field names.
Use the [DefaultNode](/kapacitor/v1.4/nodes/default_node/) and [DeleteNode](/kapacitor/v1.4/nodes/delete_node/) to finalize the fill operation if necessary.
Example:
```javascript
var maintlock = stream
|from()
.measurement('maintlock')
.groupBy('service')
var requests = stream
|from()
.measurement('requests')
.groupBy('service')
// Join the maintlock and requests streams
// The intent it to drop any points in maintenance mode.
maintlock
|join(requests)
// Provide prefix names for the fields of the data points.
.as('maintlock', 'requests')
// points that are within 1 second are considered the same time.
.tolerance(1s)
// fill missing fields with null, implies outer join.
// a better default per field will be set later.
.fill('null')
// name the resulting stream.
.streamName('requests')
|default()
// default maintenance mode to false, overwriting the null value if present.
.field('maintlock.mode', false)
// default the requests to 0, again overwriting the null value if present.
.field('requests.value', 0.0)
// drop any points that are in maintenance mode.
|where(lambda: "maintlock.mode")
|...
```
```javascript
join.fill(value interface{})
```
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### On
Join on a subset of the group by dimensions.
This is a special case where you want a single point from one parent to join with multiple
points from a different parent.
For example given two measurements:
1. building_power (a single value) -- tagged by building, value is the total power consumed by the building.
2. floor_power (multiple values) -- tagged by building and floor, values are the total power consumed by each floor.
You want to calculate the percentage of the total building power consumed by each floor.
Since you only have one point per building you need it to join multiple times with
the points from each floor. By defining the `on` dimensions as `building` we are saying
that we want points that only have the building tag to be joined with more specific points that
more tags, in this case the `floor` tag. In other words while we have points with tags building and floor
we only want to join on the building tag.
Example:
```javascript
var building = stream
|from()
.measurement('building_power')
.groupBy('building')
var floor = stream
|from()
.measurement('floor_power')
.groupBy('building', 'floor')
building
|join(floor)
.as('building', 'floor')
.on('building')
|eval(lambda: "floor.value" / "building.value")
... // Values here are grouped by 'building' and 'floor'
```
```javascript
join.on(dims ...string)
```
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### StreamName
The name of this new joined data stream.
If empty the name of the left parent is used.
```javascript
join.streamName(value string)
```
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Tolerance
The maximum duration of time that two incoming points
can be apart and still be considered to be equal in time.
The joined data point's time will be rounded to the nearest
multiple of the tolerance duration.
```javascript
join.tolerance(value time.Duration)
```
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
Chaining Methods
----------------
Chaining methods create a new node in the pipeline as a child of the calling node.
They do not modify the calling node.
Chaining methods are marked using the `|` operator.
### Alert
Create an alert node, which can trigger alerts.
```javascript
join|alert()
```
Returns: [AlertNode](/kapacitor/v1.4/nodes/alert_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Barrier
Create a new Barrier node that emits a BarrierMessage periodically
One BarrierMessage will be emitted every period duration
```javascript
join|barrier()
```
Returns: [BarrierNode](/kapacitor/v1.4/nodes/barrier_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Bottom
Select the bottom `num` points for `field` and sort by any extra tags or fields.
```javascript
join|bottom(num int64, field string, fieldsAndTags ...string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Combine
Combine this node with itself. The data is combined on timestamp.
```javascript
join|combine(expressions ...ast.LambdaNode)
```
Returns: [CombineNode](/kapacitor/v1.4/nodes/combine_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Count
Count the number of points.
```javascript
join|count(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### CumulativeSum
Compute a cumulative sum of each point that is received.
A point is emitted for every point collected.
```javascript
join|cumulativeSum(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Deadman
Helper function for creating an alert on low throughput, a.k.a. deadman's switch.
- Threshold -- trigger alert if throughput drops below threshold in points/interval.
- Interval -- how often to check the throughput.
- Expressions -- optional list of expressions to also evaluate. Useful for time of day alerting.
Example:
```javascript
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 10s and checked every 10s.
data
|deadman(100.0, 10s)
//Do normal processing of data
data...
```
The above is equivalent to this
Example:
```javascript
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 10s and checked every 10s.
data
|stats(10s)
.align()
|derivative('emitted')
.unit(10s)
.nonNegative()
|alert()
.id('node \'stream0\' in task \'{{ .TaskName }}\'')
.message('{{ .ID }} is {{ if eq .Level "OK" }}alive{{ else }}dead{{ end }}: {{ index .Fields "emitted" | printf "%0.3f" }} points/10s.')
.crit(lambda: "emitted" <= 100.0)
//Do normal processing of data
data...
```
The `id` and `message` alert properties can be configured globally via the 'deadman' configuration section.
Since the [AlertNode](/kapacitor/v1.4/nodes/alert_node/) is the last piece it can be further modified as usual.
Example:
```javascript
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 10s and checked every 10s.
data
|deadman(100.0, 10s)
.slack()
.channel('#dead_tasks')
//Do normal processing of data
data...
```
You can specify additional lambda expressions to further constrain when the deadman's switch is triggered.
Example:
```javascript
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 10s and checked every 10s.
// Only trigger the alert if the time of day is between 8am-5pm.
data
|deadman(100.0, 10s, lambda: hour("time") >= 8 AND hour("time") <= 17)
//Do normal processing of data
data...
```
```javascript
join|deadman(threshold float64, interval time.Duration, expr ...ast.LambdaNode)
```
Returns: [AlertNode](/kapacitor/v1.4/nodes/alert_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Default
Create a node that can set defaults for missing tags or fields.
```javascript
join|default()
```
Returns: [DefaultNode](/kapacitor/v1.4/nodes/default_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Delete
Create a node that can delete tags or fields.
```javascript
join|delete()
```
Returns: [DeleteNode](/kapacitor/v1.4/nodes/delete_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Derivative
Create a new node that computes the derivative of adjacent points.
```javascript
join|derivative(field string)
```
Returns: [DerivativeNode](/kapacitor/v1.4/nodes/derivative_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Difference
Compute the difference between points independent of elapsed time.
```javascript
join|difference(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Distinct
Produce batch of only the distinct points.
```javascript
join|distinct(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Ec2Autoscale
Create a node that can trigger autoscale events for a ec2 autoscalegroup.
```javascript
join|ec2Autoscale()
```
Returns: [Ec2AutoscaleNode](/kapacitor/v1.4/nodes/ec2_autoscale_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Elapsed
Compute the elapsed time between points
```javascript
join|elapsed(field string, unit time.Duration)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Eval
Create an eval node that will evaluate the given transformation function to each data point.
A list of expressions may be provided and will be evaluated in the order they are given.
The results are available to later expressions.
```javascript
join|eval(expressions ...ast.LambdaNode)
```
Returns: [EvalNode](/kapacitor/v1.4/nodes/eval_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### First
Select the first point.
```javascript
join|first(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Flatten
Flatten points with similar times into a single point.
```javascript
join|flatten()
```
Returns: [FlattenNode](/kapacitor/v1.4/nodes/flatten_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### GroupBy
Group the data by a set of tags.
Can pass literal * to group by all dimensions.
Example:
```javascript
|groupBy(*)
```
```javascript
join|groupBy(tag ...interface{})
```
Returns: [GroupByNode](/kapacitor/v1.4/nodes/group_by_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### HoltWinters
updated all latest links with latest shortcode, refactored related partial
2020-08-19 22:43:31 +00:00
Compute the holt-winters (/{{< latest "influxdb" "v1" >}}/query_language/functions/#holt-winters) forecast of a data set.
ported kapacitor 1.4
2020-07-30 16:38:32 +00:00
```javascript
join|holtWinters(field string, h int64, m int64, interval time.Duration)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### HoltWintersWithFit
updated all latest links with latest shortcode, refactored related partial
2020-08-19 22:43:31 +00:00
Compute the holt-winters (/{{< latest "influxdb" "v1" >}}/query_language/functions/#holt-winters) forecast of a data set.
ported kapacitor 1.4
2020-07-30 16:38:32 +00:00
This method also outputs all the points used to fit the data in addition to the forecasted data.
```javascript
join|holtWintersWithFit(field string, h int64, m int64, interval time.Duration)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### HttpOut
Create an HTTP output node that caches the most recent data it has received.
The cached data is available at the given endpoint.
The endpoint is the relative path from the API endpoint of the running task.
For example, if the task endpoint is at `/kapacitor/v1/tasks/<task_id>` and endpoint is
`top10`, then the data can be requested from `/kapacitor/v1/tasks/<task_id>/top10`.
```javascript
join|httpOut(endpoint string)
```
Returns: [HTTPOutNode](/kapacitor/v1.4/nodes/http_out_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### HttpPost
Creates an HTTP Post node that POSTS received data to the provided HTTP endpoint.
HttpPost expects 0 or 1 arguments. If 0 arguments are provided, you must specify an
endpoint property method.
```javascript
join|httpPost(url ...string)
```
Returns: [HTTPPostNode](/kapacitor/v1.4/nodes/http_post_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### InfluxDBOut
Create an influxdb output node that will store the incoming data into InfluxDB.
```javascript
join|influxDBOut()
```
Returns: [InfluxDBOutNode](/kapacitor/v1.4/nodes/influx_d_b_out_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Join
Join this node with other nodes. The data is joined on timestamp.
```javascript
join|join(others ...Node)
```
Returns: [JoinNode](/kapacitor/v1.4/nodes/join_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### K8sAutoscale
Create a node that can trigger autoscale events for a kubernetes cluster.
```javascript
join|k8sAutoscale()
```
Returns: [K8sAutoscaleNode](/kapacitor/v1.4/nodes/k8s_autoscale_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### KapacitorLoopback
Create an kapacitor loopback node that will send data back into Kapacitor as a stream.
```javascript
join|kapacitorLoopback()
```
Returns: [KapacitorLoopbackNode](/kapacitor/v1.4/nodes/kapacitor_loopback_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Last
Select the last point.
```javascript
join|last(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Log
Create a node that logs all data it receives.
```javascript
join|log()
```
Returns: [LogNode](/kapacitor/v1.4/nodes/log_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Max
Select the maximum point.
```javascript
join|max(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Mean
Compute the mean of the data.
```javascript
join|mean(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
<a class="top" href="javascript:document.getElementsByClassName('article-heading')[0].scrollIntoView();" title="top"><span class="icon arrow-up"></span></a>
### Median
Compute the median of the data. Note, this method is not a selector,
if you want the median point use `.percentile(field, 50.0)`.
```javascript
join|median(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### Min
Select the minimum point.
```javascript
join|min(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### Mode
Compute the mode of the data.
```javascript
join|mode(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### MovingAverage
Compute a moving average of the last window points.
No points are emitted until the window is full.
```javascript
join|movingAverage(field string, window int64)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### Percentile
Select a point at the given percentile. This is a selector function, no interpolation between points is performed.
```javascript
join|percentile(field string, percentile float64)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### Sample
Create a new node that samples the incoming points or batches.
One point will be emitted every count or duration specified.
```javascript
join|sample(rate interface{})
```
Returns: [SampleNode](/kapacitor/v1.4/nodes/sample_node/)
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### Shift
Create a new node that shifts the incoming points or batches in time.
```javascript
join|shift(shift time.Duration)
```
Returns: [ShiftNode](/kapacitor/v1.4/nodes/shift_node/)
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### Sideload
Create a node that can load data from external sources
```javascript
join|sideload()
```
Returns: [SideloadNode](/kapacitor/v1.4/nodes/sideload_node/)
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### Spread
Compute the difference between `min` and `max` points.
```javascript
join|spread(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### StateCount
Create a node that tracks number of consecutive points in a given state.
```javascript
join|stateCount(expression ast.LambdaNode)
```
Returns: [StateCountNode](/kapacitor/v1.4/nodes/state_count_node/)
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### StateDuration
Create a node that tracks duration in a given state.
```javascript
join|stateDuration(expression ast.LambdaNode)
```
Returns: [StateDurationNode](/kapacitor/v1.4/nodes/state_duration_node/)
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### Stats
Create a new stream of data that contains the internal statistics of the node.
The interval represents how often to emit the statistics based on real time.
This means the interval time is independent of the times of the data points the source node is receiving.
```javascript
join|stats(interval time.Duration)
```
Returns: [StatsNode](/kapacitor/v1.4/nodes/stats_node/)
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### Stddev
Compute the standard deviation.
```javascript
join|stddev(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### Sum
Compute the sum of all values.
```javascript
join|sum(field string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### SwarmAutoscale
Create a node that can trigger autoscale events for a docker swarm cluster.
```javascript
join|swarmAutoscale()
```
Returns: [SwarmAutoscaleNode](/kapacitor/v1.4/nodes/swarm_autoscale_node/)
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### Top
Select the top `num` points for `field` and sort by any extra tags or fields.
```javascript
join|top(num int64, field string, fieldsAndTags ...string)
```
Returns: [InfluxQLNode](/kapacitor/v1.4/nodes/influx_q_l_node/)
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### Union
Perform the union of this node and all other given nodes.
```javascript
join|union(node ...Node)
```
Returns: [UnionNode](/kapacitor/v1.4/nodes/union_node/)
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### Where
Create a new node that filters the data stream by a given expression.
```javascript
join|where(expression ast.LambdaNode)
```
Returns: [WhereNode](/kapacitor/v1.4/nodes/where_node/)
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### Window
Create a new node that windows the stream by time.
NOTE: Window can only be applied to stream edges.
```javascript
join|window()
```
Returns: [WindowNode](/kapacitor/v1.4/nodes/window_node/)
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