-`default_type` — Clause that is used in [default expression](../../sql-reference/statements/create/table.md#create-default-values) (`DEFAULT`, `MATERIALIZED` or `ALIAS`). Column contains an empty string, if the default expression isn’t specified.
-`default_expression` — Value specified in the `DEFAULT` clause.
-`comment_expression` — Comment text.
Nested data structures are output in “expanded” format. Each column is shown separately, with the name after a dot.