Views representing a data input table or uploaded CSV/XLSX files can’t be used in a join unless the table has been uploaded to a database.
{{ omni_attributes.<user_attribute> }}) can be used in joins to create access filtered joins, which can be useful when you want to keep all rows in the dataset but permiss the metadata.
Syntax
Properties
An array of relationship objects that define topic-level joins. These joins are only available within the topic where they are declared.
Examples
Join order_items to buyers
Filtered join using user attributes