timeSeriesResetsToGrid

Aggregate function that takes time series data as pairs of timestamps and values and calculates PromQL-like resets from this data on a regular time grid described by start timestamp, end timestamp and step. For each point on the grid the samples for calculating resets are considered within the specified time window.

Parameters:

start timestamp - specifies start of the grid
end timestamp - specifies end of the grid
grid step - specifies step of the grid in seconds
staleness - specified the maximum "staleness" in seconds of the considered samples

Arguments:

timestamp - timestamp of the sample
value - value of the time series corresponding to the timestamp

Return value: resets values on the specified grid as an Array(Nullable(Float64)). The returned array contains one value for each time grid point. The value is NULL if there are no samples within the window to calculate the resets value for a particular grid point.

Example: The following query calculates resets values on the grid [90, 105, 120, 135, 150, 165, 180, 195, 210, 225]:

WITH
    -- NOTE: the gap between 130 and 190 is to show how values are filled for ts = 180 according to window parameter
    [110, 120, 130, 190, 200, 210, 220, 230]::Array(DateTime) AS timestamps,
    [1, 3, 2, 6, 6, 4, 2, 0]::Array(Float32) AS values, -- array of values corresponding to timestamps above
    90 AS start_ts,       -- start of timestamp grid
    90 + 135 AS end_ts,   -- end of timestamp grid
    15 AS step_seconds,   -- step of timestamp grid
    45 AS window_seconds  -- "staleness" window
SELECT timeSeriesResetsToGrid(start_ts, end_ts, step_seconds, window_seconds)(timestamp, value)
FROM
(
    -- This subquery converts arrays of timestamps and values into rows of `timestamp`, `value`
    SELECT
        arrayJoin(arrayZip(timestamps, values)) AS ts_and_val,
        ts_and_val.1 AS timestamp,
        ts_and_val.2 AS value
);

Response:

   ┌─timeSeriesResetsToGrid(start_ts, end_ts, step_seconds, window_seconds)(timestamp, value)─┐
1. │ [NULL,NULL,0,1,1,1,NULL,0,1,2]                                                           │
   └──────────────────────────────────────────────────────────────────────────────────────────┘

Also it is possible to pass multiple samples of timestamps and values as Arrays of equal size. The same query with array arguments:

WITH
    [110, 120, 130, 190, 200, 210, 220, 230]::Array(DateTime) AS timestamps,
    [1, 3, 2, 6, 6, 4, 2, 0]::Array(Float32) AS values,
    90 AS start_ts,
    90 + 135 AS end_ts,
    15 AS step_seconds,
    45 AS window_seconds
SELECT timeSeriesResetsToGrid(start_ts, end_ts, step_seconds, window_seconds)(timestamps, values);

Note

This function is experimental, enable it by setting allow_experimental_ts_to_grid_aggregate_function=true.