Comment by matthijs

Using `truncate` in combination with `cascade` is another that I found unexpected:

"Automatically truncate all tables that have foreign-key references to any of the named tables, or to any tables added to the group due to CASCADE."

So it will simply clear out other tables that reference table to truncate, even if you have `on delete set null` and the foreign key column is null.

https://www.postgresql.org/docs/current/sql-truncate.html