flex table coalesce

[whisperstream]

I created a simple flex table and want to create a materialized "native" column for the orgId so before adding data to my flex table "json_raw", I executed the following sql statement.

alter table json_raw add column _orgId varchar(100) default coalesce(orgId, "entity.orgId", "meeting.participant.orgId", 'unknown')::varchar(100);

After importing my data, I was expecting to see the _orgId column populated, but it's empty, what gives?

Can I not use "coalesce" to materialize flex table columns or am I missing something else?

Thanks