window() function

window() groups records using regular time intervals.

The function calculates time windows and stores window bounds in the _start and _stop columns. _start and _stop values are assigned to rows based on the row’s _time value.

A single input row may be placed into zero or more output tables depending on the parameters passed into window().

This function is intended to be used when timeColumn (_time by default) is not in the group key. If timeColumn is in the group key, resulting output is confusing and generally not useful.

Window by calendar months and years

every, period, and offset parameters support all valid duration units, including calendar months (1mo) and years (1y).

Window by week

When windowing by week (1w), weeks are determined using the Unix epoch (1970-01-01T00:00:00Z UTC). The Unix epoch was on a Thursday, so all calculated weeks begin on Thursday.

Function type signature

(
    <-tables: stream[A],
    ?createEmpty: bool,
    ?every: duration,
    ?location: {zone: string, offset: duration},
    ?offset: duration,
    ?period: duration,
    ?startColumn: string,
    ?stopColumn: string,
    ?timeColumn: string,
) => stream[B] where A: Record, B: Record

Parameters

every

Duration of time between windows.

period

Duration of windows. Default is the every value.

period can be negative, indicating the start and stop boundaries are reversed.

offset

Duration to shift the window boundaries by. Defualt is 0s.

offset can be negative, indicating that the offset goes backwards in time.

location

Location used to determine timezone. Default is the location option.

timeColumn

Column that contains time values. Default is _time.

startColumn

Column to store the window start time in. Default is _start.

stopColumn

Column to store the window stop time in. Default is _stop.

createEmpty

Create empty tables for empty window. Default is false.

tables

Input data. Default is piped-forward data (<-).

Examples

• Window data into 30 second intervals
• Window every 20 seconds covering 40 second periods
• Window by calendar month

Window data into 30 second intervals

data
    |> window(every: 30s)

Window every 20 seconds covering 40 second periods

data
    |> window(every: 20s, period: 40s)

Window by calendar month

data
    |> window(every: 1mo)