If you are querying SSAS DMVs you may want to add some conditions in the query.
Something like getting all active relationships, perhaps like below:
select * from $SYSTEM.TMSCHEMA_RELATIONSHIPS where IsActive = 'true'
Running the above query on an instance of SSAS Tabular gives you the following error message:
Error: A Boolean expression is not allowed in the context …
Fixing this is quite easy, run the below query to get active relationships:
select * from $SYSTEM.TMSCHEMA_RELATIONSHIPS where IsActive
And to get inactive relationships run this one:
select * from $SYSTEM.TMSCHEMA_RELATIONSHIPS where not IsActive