Documentation

Use multiple fields in a calculation

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

To use values from multiple fields in a mathematic calculation, complete the following steps:

  1. Filter by fields required in your calculation
  2. Pivot fields into columns
  3. Perform the mathematic calculation

Filter by fields

Use filter() to return only the fields necessary for your calculation. Use the or logical operator to filter by multiple fields.

The following example queries two fields, A and B:

from(bucket: "example-bucket")
    |> range(start: -1m)
    |> filter(fn: (r) => r._field == "A" or r._field == "B")
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This query returns one or more tables for each field. For example:

_time_field_value
2021-01-01T00:00:00ZA12.4
2021-01-01T00:00:15ZA12.2
2021-01-01T00:00:30ZA11.6
2021-01-01T00:00:45ZA11.9
_time_field_value
2021-01-01T00:00:00ZB3.1
2021-01-01T00:00:15ZB4.8
2021-01-01T00:00:30ZB2.2
2021-01-01T00:00:45ZB3.3

Pivot fields into columns

Use pivot() to align multiple fields by time.

To correctly pivot on _time, points for each field must have identical timestamps. If timestamps are irregular or do not align perfectly, see Normalize irregular timestamps.

// ...
  |> pivot(rowKey: ["_time"], columnKey: ["_field"], valueColumn: "_value")
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Using the queried data above, this pivot() function returns:

_timeAB
2021-01-01T00:00:00Z12.43.1
2021-01-01T00:00:15Z12.24.8
2021-01-01T00:00:30Z11.62.2
2021-01-01T00:00:45Z11.93.3

Perform the calculation

Use map() to perform the mathematic operation using column values as operands.

The following example uses values in the A and B columns to calculate a new _value column:

// ...
    |> map(fn: (r) => ({ r with _value: r.A * r.B }))
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Using the pivoted data above, this map() function returns:

_timeAB_value
2021-01-01T00:00:00Z12.43.138.44
2021-01-01T00:00:15Z12.24.858.56
2021-01-01T00:00:30Z11.62.225.52
2021-01-01T00:00:45Z11.93.339.27

Full example query

from(bucket: "example-bucket")
    |> range(start: -1m)
    |> filter(fn: (r) => r._field == "A" or r._field == "B")
    |> pivot(rowKey: ["_time"], columnKey: ["_field"], valueColumn: "_value")
    |> map(fn: (r) => ({r with _value: r.A * r.B}))
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  • Fill window

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The future of Flux

Flux is going into maintenance mode. You can continue using it as you currently are without any changes to your code.

Read more

New in InfluxDB 3.2

Key enhancements in InfluxDB 3.2 and the InfluxDB 3 Explorer UI is now generally available.

See the Blog Post

InfluxDB 3.2 is now available for both Core and Enterprise, bringing the general availability of InfluxDB 3 Explorer, a new UI that simplifies how you query, explore, and visualize data. On top of that, InfluxDB 3.2 includes a wide range of performance improvements, feature updates, and bug fixes including automated data retention and more.

For more information, check out: