keep() function

keep() returns a stream of tables containing only the specified columns.

Columns in the group key that are not specified in the columns parameter or identified by the fn parameter are removed from the group key and dropped from output tables. keep() is the inverse of drop().

Function type signature
(<-tables: stream[A], ?columns: [string], ?fn: (column: string) => bool) => stream[B] where A: Record, B: Record

For more information, see Function type signatures.



Columns to keep in output tables. Cannot be used with fn.


Predicate function that takes a column name as a parameter (column) and returns a boolean indicating whether or not the column should be kept in output tables. Cannot be used with columns.


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


Keep a list of columns

import "sampledata"
    |> keep(columns: ["_time", "_value"])

View example input and output

Keep columns matching a predicate

import "sampledata"
    |> keep(fn: (column) => column =~ /^_?t/)

View example input and output

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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.

Flux is going into maintenance mode and will not be supported in InfluxDB 3.0. This was a decision based on the broad demand for SQL and the continued growth and adoption of InfluxQL. We are continuing to support Flux for users in 1.x and 2.x so you can continue using it with no changes to your code. If you are interested in transitioning to InfluxDB 3.0 and want to future-proof your code, we suggest using InfluxQL.

For information about the future of Flux, see the following: