Virtual Fields

Virtual Fields allow you to derive new values from your data in real time

One of the most powerful features of Axiom are Virtual Fields. With Virtual Fields, there is no need to do any up-front planning of how to structure or transform your data. Instead, send your data as-is and then use Virtual Fields to manipulate your data in real-time during queries.

The feature is also known has "derived columns/fields", however Axiom's Virtual Fields have some unique properties that make them much more powerful.

In this guide, you'll be introduced to Virtual Fields, their features, how to manage them, and how to get the best out of them.

Creating a Virtual Field

Once a dataset is selected in either the Analytics or Stream views, clicking the virtual fields icon in the toolbar will open the virtual field slide-out that displays all the virtual fields for a dataset:

Virtual fields tool button

Virtual fields slide-out

Click "Add Virtual Field" to open the virtual field editor dialog.

Virtual field editor

The editor dialog has the following components:

  • Name & Description - help your team understand what the virtual field is doing
  • Expression - this the expression that is run on every event to derive the virtual field. The expression would produce some output (from a boolean check like the example, to strings, numbers, objects or more)
  • Preview - use the preview window to test your virtual field expression against live data

The power of virtual fields is in letting you manipulate data 'on read' instead of 'on write', allowing you and your team members to adjust and update virtual fields over time as well as easily add new ones without worrying that the data has already been indexed.



Virtual Fields will be available as parameters to visualizations but, as the type of a virtual field can be any of the supported types, it is important to make sure that you are using a virtual field that produces the correct type of argument.


Virtual Fields will be available in the filter menu and all filter options will be presented. It is important to ensure that you are using a supported filter operation for the type of result your virtual field produces.

Group By

Virtual Fields can be used for segmentation in the same way as any standard field.


Virtual Fields use a rich expression language that is easy to grasp but powerful in use. This section documents the language and the functions available.

To make things easier, Virtual Fields are just APL expressions (e.g. extend alias1 = expression1, alias2 = expression2, alias3 = ... ) , and therefore Virtual Fields share all the same functions and syntax as APL expressions. To learn more about APL, click here.

Below is a list of APL scalar functions:

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