keep() function

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

Columns in the group key that are not specifed 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

Was this page helpful?

Thank you for your feedback!

Introducing InfluxDB 3.0

The new core of InfluxDB built with Rust and Apache Arrow. Available today in InfluxDB Cloud Dedicated.

Learn more

State of the InfluxDB Cloud Serverless documentation

The new documentation for InfluxDB Cloud Serverless is a work in progress. We are adding new information and content almost daily. Thank you for your patience!

If there is specific information you’re looking for, please submit a documentation issue.