FAQ: Transformations

This article covers some frequently asked questions about transformations.

I merged event A and event B together to create event C. What happens to saved charts that were querying on event A?

Any saved chart querying on event A will continue to do so after the merge. However, the event in the chart does not automatically change to event C. For any charts created after the merge, neither events A or B will populate in the chart dropdown; only event C will do this.

I merged event A and event B together to create event C. How do I bulk update the existing saved charts to now use event C?

There is no way to bulk update charts in Amplitude. However, you might try adding all charts with the old events (in this example, events A and B) to a dashboard and using Find & Replace to swap out those events for event C. Then click Save onto Charts > Update existing charts.

I merged event property A and event property B together to create event property C. What happens to saved charts that were querying on event property A and event property B?

Those charts saved before the merge will be automatically updated to query on event property C upon refresh. For example, if you have a saved chart that queries on event property A, it will instead query on event property C after a refresh, without the need for any direct action on your part. For charts created after the merge, you’ll be able to query on only the merged event property C. Event properties A and B will no longer populate in the chart dropdown.

I want to unmerge event C. What happens to the charts that use this merged event?

That depends on how you created event C in the first place.

• If you merged event A and event B into event C: Upon refresh, the chart’s user/event totals count will drop to zero.
• If you merged event A and event C into event C: Upon refresh, the chart will query on the source event C.

Can I create a new transformation from an existing transformation?

Amplitude does not currently support transformations on transformations. If this is a feature you would benefit from, please submit a feature request.

Event C is a merged event composed of source events A and B. Can I see event A and event B separately, and then event C starting at the date the transformation was made?

Transformations are retroactive, so this is unfortunately not possible.

Which value takes priority in a property merge?

Let's use an example here: For one instance of event A, you send the event property event prop = true; for another instance of event A, you send event property event_property = false. B of these event properties are then merged into EVENT PROPERTY.

In this situation, when you query on event A and group by EVENT PROPERTY, this user will populate twice. You will see one data point for the true value and one for false.