In https://hibernate.atlassian.net/browse/HHH-15288 the default DDL type mapping for Java enums mapped as ORDINAL was changed from TINYINT to SMALLINT, in order to accommodate Java enums with more than 256 members.

I suppose that this change was made because we encountered a user with an enum class which was tool-generated rather than hand-written.

But this mapping results in inefficient storage for 99.99% of all Java enums, at least on databases which have a TINYINT type, and it interferes with the TableMigrator, which is forced to treat TINYINT and SMALLINT as the same type, when they are very much not the same type from its point of view.

There’s a natural and obvious solution to this problem which is to simply look at the number of values declared by the enum when deciding the default DDL type.

It’s unfortunate that this change was already released in 6.1, and that implementing the more natural solution results in a reversion to the previous behavior from Hibernate 5 and 6.0 for almost every case, but since the previous behavior was better for all those cases, we should do it anyway.