COMMENT ON ... adds or updates the comment of an object.
COMMENT ON stores a comment about an object in the database. Each object can only have one
comment associated with it, so successive calls of
COMMENT ON to a single object will overwrite
the previous comment.
To read the comment on an object you need to query the mz_internal.mz_comments catalog table.
To comment on an object, the current role must be the owner of that object. Roles themselves do not
have owners, so to comment on a role object you must have the
CREATEROLE privilege. For more
information on ownership and privileges, see Role-based access control.
--- Add comments. COMMENT ON TABLE foo IS 'this table is important'; COMMENT ON COLUMN foo.x IS 'holds all of the important data'; --- Update a comment. COMMENT ON TABLE foo IS 'holds non-important data'; --- Remove a comment. COMMENT ON TABLE foo IS NULL; --- Read comments. SELECT * FROM mz_internal.mz_comments;