Mixpanel does not support updating or overwriting existing events by re-importing an event with the same $insert_id. The deduplication mechanism in Mixpanel ensures that if you send an event with the same combination of event, distinct_id, time, and $insert_id, only the most recently ingested event will appear in queries and reports. However, this does not update the original event's properties—instead, it will either ignore the new event (if it matches an existing one exactly) or treat it as a duplicate, depending on the deduplication phase and timing. The original event is not modified in place; Mixpanel is an append-only system for events, and event updates are not supported via the import or track APIs How Deduplication Works.
Key points from the documentation:
- Deduplication: If you send an event with the same event, distinct_id, time, and $insert_id, Mixpanel will deduplicate and only show the most recent version in reports, but it does not update the original event's properties Deduplication Mechanisms.
- No Event Updates: There is no supported way to update or patch an existing event's properties after it has been ingested. Sending a new event with the same $insert_id will not update the old event; it may be ignored or deduplicated, but not modified How Deduplication Works.
- Append-Only: Mixpanel's event store is append-only. If you need to "fix" data, the recommended approach is to delete the problematic data and re-import the corrected events with new, unique $insert_id values Reminders with ETL approach.
What you are seeing is expected behavior:
Your import call is creating a new event (or being ignored as a duplicate), not updating the existing one. If you want to correct historical data, you must delete the old event and re-import the corrected event with a new $insert_id.
Summary:
Mixpanel does not support updating existing events. The $insert_id is used for deduplication, not for updating event data. To "update" an event, delete the old one and import a new event with the correct data and a new $insert_id How Deduplication Works, Reminders with ETL approach.
