Disallow enabling/enforcing NOT NULL
Hive does not manage the data for external tables and cannot enforce constraints on these tables.
Before Upgrade to CDP
You could enable/enforce a NOT NULL constraint on an external table. For example:
CREATE EXTERNAL TABLE t(a TINYINT, b SMALLINT NOT NULL ENABLE, c INT);
After Upgrade to CDP
Enabling or enforcing a NOT NULL constraint on an external table causes an error (HIVE-18598).
Prevent errors by removing the NOT NULL constraint in CREATE TABLE or ALTER TABLE statements.