Import TimeStream's dimensions in QuickSight

I have an AWS TimeStream table defined as follows:

• user_id (varchar)
• measure_name (varchar)
• time (timestamp)
• measure_value::boolean (boolean)

(measure_name being an event name)

When I imported it in QuickSight however I only get the mesure in the fields list, not the dimension:

• measure_name
• time

My goal is to have charts of the number of unique users per day for example.

How can I import the dimensions from TimeStream?