Enriching stream data by reference data in stream analytics task

I have a task of streaming client actions. I need to add some fields from the client reference. Clients are stored in Synapse. I see that reference data is adding via file or Azur SQL in the streaming task. What's the best way to do it, via a file or a database? How do I create / update a file / table? Using the Data Factory on the trigger to insert a new client into the Synapse?