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. 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 property.

Example:

    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.

Index

Properties

Chaining Methods

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.

node.as(names ...string)

Delimiter

The delimiter for the field name prefixes. Can be the empty string.

node.delimiter(value string)

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 and DeleteNode to finalize the fill operation if necessary.

Example:

    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")
        |...

node.fill(value interface{})

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:

building_power (a single value) – tagged by building, value is the total power consumed by the building.
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:

    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'

node.on(dims ...string)

StreamName

The name of this new joined data stream. If empty the name of the left parent is used.

node.streamName(value string)

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.

node.tolerance(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. Chaining methods are marked using the | operator.

Alert

Create an alert node, which can trigger alerts.

node|alert()

Returns: AlertNode

Bottom

Select the bottom num points for field and sort by any extra tags or fields.

node|bottom(num int64, field string, fieldsAndTags ...string)

Index

Properties

Chaining Methods

Properties

As

Delimiter

Fill

On

StreamName

Tolerance

Chaining Methods

Alert

Bottom

Combine

Count

CumulativeSum

Deadman

Default

Delete

Derivative

Difference

Distinct

Elapsed

Eval

First

Flatten

GroupBy

HoltWinters

HoltWintersWithFit

HttpOut

HttpPost

InfluxDBOut

Join

K8sAutoscale

KapacitorLoopback

Last

Log

Max

Mean

Median

Min

Mode

MovingAverage

Percentile

Sample

Shift

Spread

StateCount

StateDuration

Stats

Stddev

Sum

Top

Union

Where

Window