Fill null values in data

This page documents an earlier version of InfluxDB OSS. InfluxDB 3 Core is the latest stable version.

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Use fill() to replace null values with:

data
    |> fill(usePrevious: true)

// OR

data
    |> fill(value: 0.0)

Fill empty windows of time

The fill() function does not fill empty windows of time. It only replaces null values in existing data. Filling empty windows of time requires time interpolation (see influxdata/flux#2428).

Fill with the previous value

To fill null values with the previous non-null value, set the usePrevious parameter to true.

Values remain null if there is no previous non-null value in the table.

data
    |> fill(usePrevious: true)

Given the following input:

_time_value
2020-01-01T00:01:00Znull
2020-01-01T00:02:00Z0.8
2020-01-01T00:03:00Znull
2020-01-01T00:04:00Znull
2020-01-01T00:05:00Z1.4

fill(usePrevious: true) returns:

_time_value
2020-01-01T00:01:00Znull
2020-01-01T00:02:00Z0.8
2020-01-01T00:03:00Z0.8
2020-01-01T00:04:00Z0.8
2020-01-01T00:05:00Z1.4

Fill with a specified value

To fill null values with a specified value, use the value parameter to specify the fill value. The fill value must match the data type of the column.

data
    |> fill(value: 0.0)

Given the following input:

_time_value
2020-01-01T00:01:00Znull
2020-01-01T00:02:00Z0.8
2020-01-01T00:03:00Znull
2020-01-01T00:04:00Znull
2020-01-01T00:05:00Z1.4

fill(value: 0.0) returns:

_time_value
2020-01-01T00:01:00Z0.0
2020-01-01T00:02:00Z0.8
2020-01-01T00:03:00Z0.0
2020-01-01T00:04:00Z0.0
2020-01-01T00:05:00Z1.4
query fill

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