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. Default 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)
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