Yes, the MongoDB is migrated automatically once you perform the upgrade. Just make sure you run the pre check app and solve any issues that show up.
Hi @gjunhao96
The existing data will be automatically migrated once the server is upgraded.
You can review the Server Pre-Upgrade checks here - https://community.alteryx.com/t5/Alteryx-Server-Knowledge-Base/Alteryx-Server-Pre-Upgrade-Checks/ta-...
Here is a MongoDB Schema Reference - https://help.alteryx.com/20223/server/mongodb-schema-reference