WindowNode

Warning! This page documents an old version of Kapacitor, which is no longer actively developed. Kapacitor v1.3 is the most recent stable version of Kapacitor.

Windows data over time. A window has a length defined by period and a frequency at which it emits the window to the pipeline.

Example:

    stream
        .window()
            .period(10m)
            .every(5m)
        .httpOut('recent')

The above windowing example emits a window to the pipeline every 5 minutes and the window contains the last 10 minutes worth of data. As a result each time the window is emitted it contains half new data and half old data.

NOTE: Time for a window (or any node) is implemented by inspecting the times on the incoming data points. As a result if the incoming data stream stops then no more windows will be emitted because time is no longer increasing for the window node.

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.

Align

Wether to align the window edges with the zero time. If not aligned the window starts and ends relative to the first data point it receives.

node.align()

Every

How often the current window is emitted into the pipeline.

node.every(value time.Duration)

Period

The period, or length in time, of the window.

node.period(value time.Duration)

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.

Alert

Create an alert node, which can trigger alerts.

node.alert()

Returns: AlertNode

Derivative

Create a new node that computes the derivative of adjacent points.

node.derivative(field string)

Returns: DerivativeNode

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 and results of previous expressions are made available to later expressions.

node.eval(expressions ...tick.Node)

Returns: EvalNode

GroupBy

Group the data by a set of tags.

Can pass literal * to group by all dimensions. Example:

    .groupBy(*)
node.groupBy(tag ...interface{})

Returns: GroupByNode

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 "/api/v1/task/<task_name>" and endpoint is "top10", then the data can be requested from "/api/v1/task/<task_name>/top10".

node.httpOut(endpoint string)

Returns: HTTPOutNode

InfluxDBOut

Create an influxdb output node that will store the incoming data into InfluxDB.

node.influxDBOut()

Returns: InfluxDBOutNode

Join

Join this node with other nodes. The data is joined on timestamp.

node.join(others ...Node)

Returns: JoinNode

MapReduce

Perform a map-reduce operation on the data. The built-in functions under influxql provide the selection,aggregation, and transformation functions from the InfluxQL language.

MapReduce may be applied to either a batch or a stream edge. In the case of a batch each batch is passed to the mapper idependently. In the case of a stream all incoming data points that have the exact same time are combined into a batch and sent to the mapper.

node.mapReduce(mr MapReduceInfo)

Returns: ReduceNode

Sample

Create a new node that samples the incoming points or batches.

One point will be emitted every count or duration specified.

node.sample(rate interface{})

Returns: SampleNode

Union

Perform the union of this node and all other given nodes.

node.union(node ...Node)

Returns: UnionNode

Where

Create a new node that filters the data stream by a given expression.

node.where(expression tick.Node)

Returns: WhereNode

Window

Create a new node that windows the stream by time.

NOTE: Window can only be applied to stream edges.

node.window()

Returns: WindowNode