ORM is now enforcing checkstyle within all modules. This was applied in HHH-8156. Violations were corrected in HHH-8159 and will continue to be corrected under HHH-8211 for 4.3.0.Beta3.
HHH-8175 Official support for Postgresql 9.2, Postgres Plus 9.2, and IBM DB2 10.1. Luckily, these mostly worked out-of-the-box with our existing dialects. Only a few test changes were necessary.
HHH-7797 (release 4.2.0 and 4.3.0.Beta1) changed the way uniqueness is handled. Rather than mixing "unique" on column definitions, "unique(columns...)" on table definitions, unique indexes, and unique constraints, all were changed to solely use unique constraints (DB2 is the exception -- indexes are use in certain circumstances). Follow-up issues were corrected in this release: HHH-8162 and HHH-8178.
More details about HHH-8162: Since unique constraints are now the default, special handling was necessary within SchemaUpdate. The method used is configurable, selected with the "hibernate.schema_update.unique_constraint_strategy" property. DROP_RECREATE_QUIETLY is the default. It attempts to drop, then (re-)create each unique constraint within your model. All errors and exceptions (constraint doesn't exist, constraint already existed, etc.) are ignored. RECREATE_QUIETLY is the same, but does not attempt the drop. SKIP will not attempt to drop or create unique constraints at all on the SchemaUpdate.
HHH-7617 Support for generating Eclipse IDE projects was improved. Please see this post for more info.
HHH-7943 improved the c3p0, proxool, ehcache, and infinispan strategies. All are now selectable in configurations by both classname and a short name. Further, their strategies were integrated as OSGi services. Note that HHH-7943 has multiple follow-on tickets due to classloader issues found with many of the 3rd party bundles.
HHH-7993 supports basic OSGi Bundle scanning to automatically discover entities and mappings in your persistence unit bundle.
HHH-8183 supports synonyms in schema validation. Enable the capability with the "hibernate.synonyms=true" property (disabled by default).