Two changes to Message Queue's persistent store format have been made to improve performance. One change is to the file store, the other to the JDBC store.
Transaction Information in the file store
The format of transaction state information stored in the Message Queue file-based persistent store has been changed to reduce disk I/O and improve the performance of JMS transactions.
Oracle JDBC Store
In previous versions of Message Queue, the store schema used with Oracle used the LONG RAW data type to store message data. In Oracle 8, Oracle introduced the BLOB data types and deprecated the LONG RAW type. Message Queue 3.7 UR1 switches to the BLOB data type to improve performance and supportability.
Because these changes impact store compatibility, the store version has been changed from 350 to 370. Message Queue 3.7 UR1 supports automatic conversion of the persistent store from the older 200 and 350 versions to the 370 version - both for JDBC and for file based stores. The first time imqbrokerd starts, if the utility detects an older store it will migrate the store to the new format, leaving the old store behind.
If you should need to roll back this upgrade, you can uninstall Message Queue 3.7 UR1 and then reinstall the version you were previously running. Since the older copy of the store is left intact, the broker can run with the older copy of the store.