are we able to define what distinct ID Mixpanel should use?

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In Mixpanel, the ability to define what distinct ID is used depends on your implementation method and which ID Merge API your project is using.

When using server-side libraries (like Go, Node.js), you need to generate and manage the distinct_id yourself: - For server-side tracking, Mixpanel doesn't automatically generate IDs like it does with client-side SDKs Mixpanel SDKs: Go - You'll need to generate and include the distinct_id in your events and profile data Mixpanel SDKs: Node.js

For client-side SDKs (Web, iOS, Android), the behavior depends on which ID Merge API your project uses:

- You can influence the distinct_id by setting $device_id and $user_id properties - When only $device_id is present, it becomes the distinct_id - When $user_id is present, it becomes the distinct_id Identifying Users (Simplified)

- The distinct_id is programmatically selected by Mixpanel from the identity cluster - This selection is random and not user-configurable - Any ID in the cluster can be used for ingestion, but only the canonical distinct_id can be used in queries Identifying Users (Original)

If you need to ensure you can always query by your own chosen user ID, set it as a separate user profile property and event property, regardless of which ID becomes the distinct_id Identifying Users (Original).You can check which Identity Merge API your project is using in your project settings.

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